The Metropolitan Police launched an international appeal after Zou, 28, was convicted of drugging and raping 10 women following a trial at the Inner London Crown Court last month.
Detectives have not confirmed whether the 23 people who have come forward add to their estimates that more than 50 other women worldwide may have been targeted by the University College London student.
Metropolitan Police commander Kevin Southworth said: "We have victims reaching out to us from different parts of the globe.
"At the moment, the primary places where we believe offending may have occurred at this time appears to be both in England, here in London, and over in China."
Zou lived in a student flat in Woburn Place, near Russell Square in central London, and later in a flat in the Uncle building in Churchyard Row in Elephant and Castle, south London.
Read more: How a student described as 'smart and charming' was unmasked as a prolific sexual predator
He had also been a student at Queen's University Belfast, where he studied mechanical engineering from 2017 until 2019. Police say they have not had any reports from Belfast but added they were "open-minded about that".
"Given how active and prolific Zou appears to have been with his awful offending, there is every prospect that he could have offended anywhere in the world," Mr Southworth said.
"We wouldn't want anyone to write off the fact they may have been a victim of his behaviour simply by virtue of the fact that you are from a certain place.
"The bottom line is, if you think you may have been affected by Zhenhao Zou or someone you know may have been, please don't hold back. Please make contact with us."
Zou used hidden or handheld cameras to record his attacks, and kept the footage and often the women's belongings as souvenirs.
He targeted young, Chinese women, inviting them to his flat for drinks or to study, before drugging and assaulting them.
Zou was convicted of 11 counts of rape, with two of the offences relating to one victim, as well as three counts of voyeurism, 10 counts of possession of an extreme pornographic image, one count of false imprisonment and three counts of possession of a controlled drug with intent to commit a sexual offence, namely butanediol.
Mr Southworth said: "Of those 10 victims, several were not identified so as we could be sure exactly where in the world they were, but their cases, nevertheless, were sufficient to see convictions at court.
"There were also, at the time, 50 videos that were identified of further potential female victims of Zhenhao Zou's awful crimes.
"We are still working to identify all of those women in those videos.
"We have now, thankfully, had 23 victim survivors come forward through the appeal that we've conducted, some of whom may be identical with some of the females that we saw in those videos, some of whom may even turn out to be from the original indicted cases."
Mr Southworth added: "Ultimately, now it's the investigation team's job to professionally pick our way through those individual pieces of evidence, those individual victims' stories, to see if we can identify who may have been a victim, when and where, so then we can bring Zou to justice for the full extent of his crimes."
Mr Southworth said more resources will be put into the investigation, and that detectives are looking to understand "what may have happened without wishing to revisit the trauma, but in a way that enables [the potential victims] to give evidence in the best possible way."
The Metropolitan Police is appealing to anyone who thinks they may have been targeted by Zou to contact the force either by emailing survivors@met.police.uk, or via the major incident public portal on the force's website.
It is no joke for him and it is no joke for governments globally as they brace for his tariff announcements.
It is stunning how little we know about the plans to be announced in the Rose Garden of the White House later today.
It was telling that we didn't see the President at all on Tuesday. He and all his advisers were huddled in the West Wing, away from the cameras, finalising the tariff plans.
Follow the events of Liberation Day live as they unfold
Three key figures are central to it all.
Treasury Secretary Scott Bessent is the so-called 'measured voice'. A former hedge fund manager, he has argued for targeted not blanket tariffs.
Peter Navarro is Trump's senior counsellor for trade and manufacturing. A long-time aide and confidante of the president, he is a true loyalist and a firm believer in the merits of tariffs.
His economic views are well beyond mainstream economic thought - precisely why he appeals to Trump.
The third key character is Howard Lutnick, the commerce secretary and the biggest proponent of the full-throttle liberation day tariff juggernaut.
The businessman, philanthropist, Trump fundraiser and billionaire (net worth ranging between $1bn and $2bn) has been among the closest to Trump over the past 73 days of this presidency - frequently in and out of the West Wing.
If anything goes wrong, observers here in Washington suspect Trump will make Lutnick the fall guy.
What are Donald Trump's tariffs, what is 'liberation day' and how does it all affect the UK?
And what if it does all go wrong? What if Trump is actually the April fool?
"It's going to work..." his press secretary said when asked if it could all be a disaster, driving up the cost of living for Americans and creating global economic chaos.
"The president has a brilliant team who have been studying these issues for decades and we are focussed on restoring the global age of America..." Karoline Leavitt said.
Dancing to the president's tune
My sense is that we should see "liberation day" not as the moment it's all over in terms of negotiations for countries globally as they try to carve out deals with the White House. Rather it should be seen as the start.
Trump, as always, wants to be seen as the one calling the shots, taking control, seizing the limelight. He wants the world to dance to his tune. Today is his moment.
But beyond today, alongside the inevitable tit-for-tat retaliation, expect to see efforts by nations to seek carve-outs and to throw bones to Trump; to identify areas where trade policies can be tweaked to placate the president.
Even small offerings which change little in a material sense could give Trump the chance to spin and present himself as the winning deal maker he craves to be.
One significant challenge for foreign governments and their diplomats in Washington has been engaging the president himself with proposals he might like.
Negotiations take place with a White House team who are themselves unsure where the president will ultimately land. It's resulted in unsatisfactory speculative negotiations.
Too much faith placed in the 'special relationship'?
The UK believes it's in a better position than most other countries globally. It sits outside the EU giving it autonomy in its trade policy, its deficit with the US is small, and Trump loves Britain.
It's true too that the UK government has managed to accelerate trade conversations with the White House on a tariff-free trade partnership. Trump's threats have forced conversations that would normally sit in the long grass for months.
Yet, for now, the conversations have yielded nothing firm. That's a worry for sure. Did Keir Starmer have too much faith in the 'special relationship'?
Downing Street will have identified areas where they can tweak trade policy to placate Trump. Cars maybe? Currently US cars into the UK carry a 10% tariff. Digital services perhaps?
US food? Unlikely - there are non-tariff barriers on US food because the consensus seems to be that chlorinated chicken and the like isn't something UK consumers want.
Easier access to UK financial services maybe? More visas for Americans?
For now though, everyone is waiting to see what Trump does before they either retaliate or relent and lower their own market barriers.
Aluminium, steel, cars and champagne have all been in his firing line, while China, Canada and Mexico are the countries targeted with the heaviest costs.
Along the way, there have been threats, pauses and postponements.
So what are tariffs, what is in the pipeline - and what could all this mean for the UK?
What are tariffs and why is Trump threatening to use them?
Tariffs are taxes on goods imported into the US.
It is the importers buying the goods who pay the tariffs - therefore, American companies.
Ultimately, the intent is to protect US manufacturing and bolster jobs by making foreign-made products less attractive.
However, there is a knock-on effect: to compensate for tariffs, companies put up their prices, so customers end up paying more for goods.
Tariffs can also damage foreign countries as they make their products pricier and harder to sell.
In his second term, Mr Trump has frequently used them - or the threat of them - as a trade weapon.
They are a key part of Mr Trump's efforts to reshape global trade relations, and he plans to impose a swathe of what he calls "reciprocal" taxes that would match tariffs levied by other nations.
Tariffs were also part of his playbook in his first term, when he imposed taxes on most goods coming from China and used them as a bargaining chip to force Canada and Mexico to renegotiate a North American trade pact.
On his first day back in office, the US president promised 25% tariffs on all products coming into the US from its nearest neighbours Mexico and Canada - ostensibly to force the countries to tackle illegal migration and fentanyl crossing the border.
What is liberation day?
Mr Trump has branded 2 April "liberation day", when he could unveil the reciprocal tariffs on countries deemed to be giving the US a bad deal on trade.
The extent of potential tariffs and countries affected remains unclear, with Mr Trump at times sending mixed messages.
On 30 March, he said "all countries" could expect to be hit by tariffs.
Speaking from Air Force One, the US president rubbished a question from a reporter who asked whether it was true he was planning on targeting between 10 and 15 countries.
"Who told you 10-15 countries? You didn't hear it from me," he said.
When pressed on how many he was planning to hit, he said: "You'd start with all countries, let's see what happens."
Two days prior, he said he was open to carving out deals with countries seeking to avoid US tariffs, but that those agreements would be negotiated after 2 April.
He had previously said he "may give a lot of countries breaks, but it's reciprocal", adding: "We might be even nicer than that."
How could the UK be affected?
The UK hopes an economic deal with the US will spare the country from some of the tariffs.
Sir Keir Starmer and Mr Trump have had "productive negotiations" towards a UK-US "economic prosperity deal", Downing Street has said.
The two leaders discussed a possible deal in a phone call on Sunday and agreed negotiations will "continue at pace", according to a statement released on Sunday 30 March.
The day before the so-called "liberation day", Sir Keir told Sky News political editor Beth Rigby the UK was "working hard on an economic deal" with the US and said "rapid progress" has been made.
But, he admitted: "Look, the likelihood is there will be tariffs. Nobody welcomes that, nobody wants a trade war.
"But I have to act in the national interest and that means all options have to remain on the table."
Sir Keir added: "We are discussing economic deals. We're well advanced.
"These would normally take months or years, and in a matter of weeks, we've got well advanced in those discussions, so I think that a calm approach, a collected approach, not a knee-jerk approach, is what's needed in the best interests of our country."
Mr Trump has not explicitly said the UK is in his sights for further tariffs.
Data shows no great trade imbalances - the gap between what you import and export from a certain country - and UK figures show no trade deficit with the United States.
UK ministers have previously suggested this could be good news for avoiding new levies.
But the tariffs Mr Trump has already announced would have a big impact on the UK - particularly the car tariff.
Jonathan Reynolds, the business and trade secretary, earlier told Sky News he is "hopeful" the tariffs can be reversed soon.
But he warned: "The longer we don't have a potential resolution, the more we will have to consider our own position in relation to [tariffs], precluding retaliatory tariffs."
He added the government was taking a "calm-headed" approach in the hope a deal can be agreed, but said it is only "reasonable" that retaliatory tariffs are an option, echoing Sir Keir's sentiments over the weekend.
What tariffs have already been announced?
Some tariffs have already come into effect, while Mr Trump has confirmed some that will come in on 2 April.
He has said a 25% tariff on all cars imported to the US will come into effect, with a similar tariff on car parts expected to follow in May.
This could prove even more complicated for American car makers, who source components from around the world even if the vehicle is made in the US.
But Mr Trump has insisted the move will "continue to spur growth", pointing to plans from Hyundai - the South Korean car maker - to build a $5.8bn (£4.5bn) steel plant in Louisiana.
The tariff could have a huge impact on the UK's car industry, including on manufacturers such as Jaguar Land Rover, Aston Martin and Rolls-Royce.
Official data shows the US is the UK car sector's largest single market by country, accounting for £6.4bn worth of car exports in 2023 - 18.4% of the total.
Trump has also said he will place a 25% tariff on all imports from any country that buys oil or gas from Venezuela, which includes the US itself - in addition to imposing new tariffs on the South American country.
On 12 March, a 25% tariff on all steel and aluminium imports to the US came into effect, affecting UK products worth hundreds of millions of pounds.
The move came after he placed a 10% tax on all imports from China, which he later doubled to 20%.
He placed 25% tariffs on Mexico and Canada, but paused them for a month two days after they came into effect, meaning they are set to resume on 2 April.
The pause did not fully cover a tariff of 10% on Canadian energy products.
What has been the global response to tariffs?
There has widely been condemnation of the tariffs, especially from countries worst affected like Mexico and Canada.
Some have imposed, or threatened to impose, retaliatory tariffs.
China has already hit back with retaliatory tariffs covering a range of US goods, including a 15% tariff on coal and liquefied natural gas products, a 10% tariff on US crude oil and tariffs of up to 15% on key US farm exports.
Canada imposed tariffs of its own on US products, including a 25% reciprocal tariff on US steel and aluminium products and tariffs worth an estimated C$29.8bn (£16bn) on a wide range of US products including orange juice, peanut butter, alcohol, coffee and clothing.
Read more on tariffs:
It may be harder for the UK to trump metals tariffs
Stock markets tumble as Trump tariffs loom
The European Union has said it will impose retaliatory tariffs on the US, but when they will come into force is unknown.
The European Commission initially threatened to impose "countermeasures" affecting €26bn (£21.9bn) of US goods from 1 April, but later delayed this until the middle of April.
The bloc said the delay was because it wanted "additional time for discussions" with the US after Mr Trump threatened a 200% tariff on EU alcohol - including wine and champagne - if the bloc imposed duties on US whiskey.
Any tariffs imposed by the bloc would not only impact US steel and aluminium products, but also textiles, home appliances, agricultural goods and whiskey.
Why tariffs could cost you - even if Trump spares UK
Even if no tariffs are put on all UK exports to the US, consumers globally will still be impacted by the wider trade war, particularly in the US.
Economists believe that tariffs will raise costs in the US, sparking a wave of inflation that will keep interest rates higher for longer. The US central bank, the Federal Reserve, is mandated to act to bring inflation down.
More expensive borrowing and costlier goods and services could bring about an economic downturn in the US and have knock-on effects in the UK.
Forecasts from the National Institute of Economic and Social Research (NIESR) predict lower UK economic growth due to higher global interest rates.
It estimated that UK GDP (a measure of everything produced in the economy) could be between 2.5% and 3% lower over five years and 0.7% lower this year.
The Centre for Inclusive Trade Policy thinktank said a 20% across-the-board tariff, impacting the UK, could lead to a £22bn reduction in the UK's US exports, with the hardest-hit sectors including fishing and mining.
The crew of a Royal Navy destroyer is on high alert for enemy drones - launched from the air and from the water.
"Maximum air threat," the voice says.
A helicopter, already airborne, uses a missile to take out an incoming drone from a distance, while the ship's guns open fire on a small uncrewed vessel racing towards it.
The action, using live rounds, unfolded on Tuesday off the Welsh coast as HMS Dauntless, a Type 45 destroyer, took part in an exercise to prepare for a major deployment to Asia in the coming weeks alongside one of the UK's two aircraft carriers.
The voyage could take the carrier strike group through hostile waters, including within range of Iranian-backed Houthi rebels in Yemen.
It means the heavily-armed destroyer - a key layer of defence for HMS Prince of Wales - may come under attack for real.
Luke Pollard, the armed forces minister, said the ship was well prepared.
"If anyone were to threaten our carrier, they should be in no doubt that we possess formidable capabilities to defend ourselves, to defend every ship in that task force," he told Sky News, speaking onboard Dauntless, having watched part of the training.
Escalating tensions between Washington and Tehran may also impact the long-planned trip.
Donald Trump has threatened to bomb Iran if the regime does not reach an agreement with Washington over its nuclear programme.
Asked whether the UK would divert its warships to support the US - if requested - should it attack Iran, Mr Pollard said: "The advantage of naval power is that it always presents options, so there's always options in support of our national security objectives.
"That's why, when the carrier sails shortly for the Indo-Pacific, there's options for her entire deployment as to how we use that power."
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Practising their defensive drills, the crew of HMS Dauntless, commanded by Commander Ben Dorrington, used radars and binoculars to scan the area for enemy drones.
A large portion of the exercise involved simulated threats, such as pretend swarms of aerial drones and uncrewed vessels, cruise missiles and hostile jets
But there were also a number of real unmanned aerial systems and uncrewed attack boats for training. Drone vessels, packed with explosives, are an emerging maritime threat. Ukraine has used them to great effect against Russia's Black Sea Fleet.
Sky News watched as fixed guns on one side of the destroyer opened fire on an uncrewed vessel that was playing the part of the enemy.
The weapons included a cannon called Phalanx, which can pump out 3,000 rounds of armour-piercing shells a minute.
Rounds could be seen piercing the water. The gunners then took out the boat, with flames and smoke rising out of it.
Despite some cutting-edge capabilities, the Royal Navy's fighting capacity is increasingly finite after decades of defence cuts.
The government has announced plans to increase defence spending to 2.5% of GDP by 2027, but many defence insiders say the increase is too small and too slow.
Mr Pollard defended the policy, pointing to an extra £5bn in the budget this year.
"We know the world is more dangerous, we know threats towards the UK and our allies are increasing, and that's why we're investing in defence."
A review by former Labour adviser Dan Corry into Britain's sluggish system of green regulation has concluded that existing environmental regulators should remain in place, while rejecting a "bonfire of regulations".
But Mr Corry suggested there might be circumstances in which the government look at changing the wildlife and habit rules inherited from the EU, which protect individual species.
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These lie at the centre of the controversy of a £120m bat tunnel - the shed in Aylesbury which protects a rare breed from future high speed trains.
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The government has now explicitly ruled out any such change in this parliament.
Campaigners have questioned whether the changes go far enough and will make a major difference to the rate and scale of building in the UK.
Speaking to Sky News, Environment Secretary Steve Reed insisted that accepting nine of the recommendations from the Corry review would amount to wholesale reform.
The minister said: "We can get a win-win for economic growth and for nature. And that is why we are moving ahead with proposals such as appointing a lead regulator for major developments so that the developers don't have to navigate the architecture of multiple regulators.
"They just work for a single regulator who manages all the others on their behalf. Simplifying the online planning portal.
"These are huge changes that will save developers billions of pounds and speed up decisions doing damage to the environment."
Mr Reed insisted that there would be "no more bat tunnels" built, even though the Corry review suggests that more work needs to be done to look again at the relevant guidance.
It says: "Rapidly reviewing the existing catalogue of compliance guidance, including on protecting bats, will identify opportunities to remove duplication, ambiguity or inconsistency.
"Natural England has already agreed to review and update their advice to Local Planning Authorities on bats to ensure there is clear, proportionate and accessible advice available."
The review will mean:
• Appointing one lead regulator for every major infrastructure project, like Heathrow expansion
• A review on how nature rules are implemented - but not the rules themselves
• Insisting regulators focus more on government priorities, particularly growth
Economist and former charity leader Mr Corry, who led the review, said it shows that "simply scrapping regulations isn't the answer".
"Instead we need modern, streamlined regulation that is easier for everyone to use. While short-term trade-offs may be needed, these reforms will ultimately deliver a win-win for both nature and economic growth in the longer run."
However, Sam Richards from Britain Remade, a thinktank trying to get Britain growing, said that while the steps are welcome, the number of regulators that report to the environment department would remain the same before and after the review. He questioned whether this would have the impact ministers claimed.