Police today confirmed that the fire was started deliberately - they say petrol poured through the letterbox was used to start the blaze.

In tears, Mick Philpott spoke to the media in Derby five days after Jade Philpott, 10, John, nine, Jack, aged seven, Jessie, six, and five-year-old Jayden, all died from the effects of smoke.

His 13-year-old son Duwayne died of his injuries in Birmingham Children's Hospital at the weekend.

Flanked by his wife Mairead, Mr Philpott told reporters about how Duwayne's organs had been donated for transplant.

He said: "If you can save another child, that makes us happy and it takes a bit of the pain away."

The couple thanked members of the local community for their "overwhelming" support since the tragedy.

"We grew up in a community that's been through a lot of problems with violence and to see this community come together like it has, it's too overwhelming," said Mr Philpott.

He also praised the emergency services. "Those poor gentlemen from the fire brigade, who saw what we saw, my heart goes out to them."

The children were asleep in their beds upstairs when the fire broke out at the semi-detached house in Allenton, Derby in the early hours of the morning.

Mr Philpott, aged 54, made a "valiant" attempt to save them, police said.

A 28-year-old woman and 38-year-old man, both local, were arrested by officers but were released without charge on Saturday.

Sky's Midlands correspondent Lisa Dowd, who was at the news conference, said Assistant Chief Constable Steve Cotterill later told reporters that he understood Mr Philpott was woken by a smoke alarm after a "reasonable quantity of petrol" was poured through the letterbox.

The couple had been sleeping downstairs.

But Mr Cotterill said he had not spoken to Mr and Mrs Philpott in detail about the events yet due to their distress.

He said "any reasonable individual" would know the harm the petrol could cause and that the family had "celebrity status" so people would be well aware that a large number of children would have been in the house.

Mr Cotterill said he did not know what the motive was. Police would "unpick the scene piece by piece".

He paid tribute to the couple's courage and said that the news conference had been Mr Philpott's idea because he wanted to pay tribute to those who helped him try to rescue his children.

Police are urging locals to check gardens and hedges for discarded petrol containers.

They also want petrol station staff to come forward if they sold containers to anyone in the days before the blaze.