The Lebanese army and state media said that an Israeli commando force landed on the mountains along the border with Syria before heading to the eastern town of Nabi Chit, where they clashed with Hezbollah and local fighters.
Lebanon's health ministry said at least 41 people were killed and 40 wounded.
Lebanese army commander General Rudolphe Haikal claimed that the Israeli force was dressed in Lebanese army uniforms, and used ambulances with signs of Hezbollah's Islamic Health Organization, during the operation.
A resident of Nabi Chit told The Associated Press that the Israeli force entered the town and dug up a grave in a cemetery before it left.
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Hezbollah said its members clashed with the Israeli force, and that Israel's air force conducted around 40 airstrikes in the area in order for the unit on the ground to be able to withdraw.
The Israeli army's Arabic spokesman Avichay Adraee posted on social media that the force did not find Arad's remains.
Arad went missing after parachuting from a fighter jet that crashed in Lebanon in 1986. He had been involved in an operation against suspected Palestinian militants.
A Shiite Muslim faction called the Believers' Resistance captured Arad alive after he landed, and released some photos of him early on before all traces of him disappeared.
Arad was believed to have been held in Nabi Chit until 1988, after which he went missing following a fierce battle between Hezbollah fighters and Israeli troops in the village of Meidoun, further south.
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Arad's wife Tami, meanwhile, has urged Israel's leaders not to endanger the lives of Israeli soldiers in their search for him.
"Our desire to know what happened to Ron stops the moment it endangers Israeli soldiers," she wrote on Facebook.
"For 40 years, we have lived with the fact that Ron is missing, and we want to know what happened to Ron, but not at any price. The sanctity of life is above any closing of the circle of certainty for us."
Adraee said the Israeli force did not suffer any casualties in the operation.
The 52-year-old was taken to hospital after being found in a pool of blood following an alleged attack by an unknown inmate on 26 February.
The former school caretaker was attacked in a workshop with a metal bar at HMP Frankland in County Durham.
Police said earlier that a man in his mid-40s was being investigated over the incident.
Huntley was convicted of the murders of 10-year-olds Holly Wells and Jessica Chapman in Soham, Cambridgeshire, in 2002.
He killed them after they left a family barbecue to buy sweets, then dumped their bodies in a ditch.
Huntley was convicted of the murder of both girls in December 2003 and sentenced to two terms of life imprisonment.
Durham Constabulary confirmed Huntley had died in hospital on Saturday morning.
"Ian Huntley, 52, was taken to hospital with serious injuries following an incident in the workshop on the morning of Thursday, February 26," a spokesman said.
"A police investigation into the circumstances of the incident is ongoing.
"A file is being prepared for the Crown Prosecution Service for consideration for charges."
A Ministry of Justice spokesperson said: "The murders of Holly Wells and Jessica Chapman remains one of the most shocking and devastating cases in our nation's history, and our thoughts are with their families."
According to The Sun, the attack last month left Huntley blind, and he was not expected to regain consciousness.
The newspaper quoted a source as saying: "Huntley never recovered from the battering and never stood much of a chance of doing so."
After the attack, the murderer's only daughter, Samantha Bryan, 27, told The Sun on Sunday that "there's a special place in hell waiting for him".
Huntley had been injured in a previous attack at HMP Frankland in 2010, where an inmate slashed his throat with a makeshift knife. The prisoner was jailed for life over the incident.
The crime made Huntley one of Britain's most reviled killers, with the murder shocking the nation and raising questions about how a man with a history of sexual allegations against him had been allowed to work at a school.
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The best friends were dressed in matching Manchester United shirts when he lured them into his home and killed them.
Their bodies were not found for 13 days, with their disappearance and the resulting police search drawing national media attention.
Reporter Brian Farmer, who worked for the Press Association in East Anglia at the time, interviewed Huntley at the time and was so concerned by what he heard, he went to the police afterwards.
Farmer was surprised when Huntley began to tell him how he imagined the girls would react to a stranger approaching them, despite not knowing them or working in their school.
The journalist had been trying to interview Maxine Carr, a teaching assistant at the girls' school, who was living with Huntley when the interaction took place.
The UK, France and Spain are among the nations sending warships, jets and troops to the region to bolster their defences and protect their allies, while states across the Middle East, as well as Cyprus, Turkey and Azerbaijan, have been affected by Iranian drones and missiles.
The US is also not restricting its strikes against the Islamic regime to any geographical boundary, with an American submarine sinking an Iranian warship off the coast of Sri Lanka.
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Warnings about World War Three have long been voiced ever since Russia launched its full-scale invasion of Ukraine more than four years ago.
That was because of fears the conflict could spill over into neighbouring NATO states in Europe, drawing the nuclear-armed alliance into direct confrontation with Moscow, which also has a large arsenal of nuclear weapons.
This risk remains.
But the world has just become even more combustible because of the US president's decision, along with Israel, to attack Iran with a ferocity of firepower that exceeded the opening days of the US-led invasion of Iraq in 2003.
Since the fighting began on 28 February, the US military says it has struck more than 3,000 targets. Israeli warplanes have also conducted hundreds of sorties. The onslaught claimed the life of Ali Khamenei, the supreme leader of Iran, in the opening salvo.
In response, Iranian forces have fired multiple waves of missiles and drones against US forces in the region and Israel, but also against Gulf states, including the United Arab Emirates, Qatar and even Oman, despite Muscat having played an important role in negotiating between Tehran and Washington in the past.
The Iranian president on Saturday issued an apology to his neighbours, and said there would be no more strikes against them, provided that no attacks targeting his country originate from US forces on their respective territories. However, Iranian munitions have continued to hit Gulf states, though perhaps not at the same intensity.
The US military has said it has already seriously degraded Iran's ability to attack, with Mr Trump warning of even more devastating strikes to come
Yet the Iranian side is vowing to keep fighting rather than heed American demands to surrender.
Pete Hegseth, who describes himself as the US secretary of war, has said the American operation could last eight weeks - an indication of the sheer number of targets the US must have amassed.
Mr Trump has vowed to destroy all Iranian missile and naval capabilities, and to prevent the country from ever having a nuclear weapons programme.
However, the longer the attacks continue, the greater the risk of miscalculation that could ignite an even wider war.
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The battle lines in the Middle East already have crossovers with Russia's war in Europe, though they have not really reached Asia, with China so far giving a muted response.
Moscow has for years received weapons from Tehran, while Kyiv is backed by a coalition of allies, including the UK, France, Germany, Australia and Canada. The US is also an important source of munitions for Ukraine.
Now reports are emerging of Russian forces providing intelligence to Iran that could help Tehran target American warships, troops and bases in the Gulf. At the same time, the US has asked Ukrainian soldiers for support in countering Iranian drones.
These alliances and allegiances underline the complexity of the chaos - and just how dangerous a moment this is.
The militant gang members were shot dead during a gun battle with troops in Danmusa, in the state of Katsina in northern Nigeria, on Friday.
An army captain and two soldiers were also killed in the fighting, officials said.
State security commissioner Nasir Mua'zu said the group initially made a failed attempt to take the animals on Thursday.
"Seeking revenge, the bandits returned in large numbers on March 6," he said.
"What followed was an intense and fierce battle. The army successfully neutralised all 45 bandits."
Members of the local community helped repel the initial attempted theft on Thursday before the "prolonged" battle the following day, according to Nigerian media.
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The military in the West African country has recently been struggling to maintain security amid a spate of attacks by different armed groups.
They include Islamist groups such as Lakurawa, Boko Haram and its breakaway faction known as Islamic State West Africa Province.
Several "bandit" gangs, specialising in kidnapping for ransom and illegal mining, have also been blamed for attacks in the north of the country.
Last month, the violence prompted the US to send around 100 troops to Nigeria to provide advice and training to its army on tackling the threats.
In another attack on Friday, more than 300 people, including women and children, were abducted by militants from the town of Ngoshe in the country's northeast.
Several thousand people have been killed as a result of militant violence across the country, according to the UN, with the government accused of not doing enough to protect its citizens.
The number of dead includes two children, the region's governor Oleh Syniehubov said.
Mr Syniehubov said the ballistic missile damaged a five-storey residential building in Kharkiv.
More than 15 people were also injured in the strike, including three children, officials said.
Rescuers have begun clearing the rubble and continue their search for more people who may have been buried when the building collapsed.
The impact destroyed the entrance and damaged the upper floors of a neighbouring building.
The deaths came as Russia unleashed a barrage of drones and missiles at Ukraine overnight on Saturday.
Across the city, 19 residential buildings, electricity distribution lines, commercial and administrative premises and cars were also damaged by the Russian attacks, Mr Syniehubov said.
Ukrainian President Volodymyr Zelenskyy said Russia had launched 480 drones and 29 missiles targeting vital infrastructure across the country.
He said most of the drones were Shaheds, a type of Iranian-designed drone which Russia has used to batter Ukraine repeatedly since the full-scale invasion began four years ago.
Mr Zelenskyy said Russia had targeted energy facilities in Kyiv, Khmelnytskyi and Chernivtsi regions, and the railway in the Zhytomyr region.
Damage was reported in the Dnipro, Zaporizhia, Vinnytsia, Odesa, Poltava, Sumy, and Cherkasy regions, Mr Zelenskyy said.
Air defence systems downed 19 missiles and 453 drones, with hits from nine missiles and 26 strike drones recorded at 22 locations, preliminary data shows.
But nine missiles and 26 attack drones hit 22 sites, it said.
"There should be a response from partners to these savage strikes against life," Mr Zelenskyy said on Telegram.
"Russia has not abandoned its attempts to destroy Ukraine's residential and critical infrastructure, and therefore support should continue."
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Mr Zelenskyy urged the country's partners to continue air defence and weapons supplies.
In the Kyiv region, three people were injured, heating was disconnected in 2,806 apartment buildings and damage from debris was reported across three districts, local authorities said.
In the southern Odesa region, 80 firefighters were called in to battle major blazes at infrastructure facilities following a drone attack.
Russia has launched its own large-scale domestic production of Shahed drones, which have played a prominent role in Iran's response to US-Israeli strikes, which began a week ago.
A new round of US-brokered talks between Russia and Ukraine, planned for this week, have been postponed due to the war in the Middle East.