Search teams at Grenfell Tower are said to have discovered up to 42 bodies of victims in a single room.
They are reported to have made the grim discovery during the painstaking fingertip search of the building in White City over the last few days.
The claim was made in a YouTube video by a man as he stood in front of the charred remains.
He said: ‘I’ve got a friend who works for the fire brigade here at Ladbroke Grove, yeah.
‘Yesterday on the phone he said they found about 42 bodies in one room, all hiding together. No-one knows that.’
‘It’s only because we know the brother, he’s a fireman, that he told us this – but he can’t tell you lot that.
‘He can’t come out because he’ll probably get the sack or something. But they said they found 42 bodies in one room, bruv, in one room. From children to old people.’
A 52-year-old woman is the fifth victim of the Grenfell Tower fire to have been named, after Scotland Yard announced the death toll had risen to 79.
Khadija Khalloufi, who lived in Grenfell Tower, had not been seen since a huge blaze destroyed the 24-storey tower block in west London last Wednesday.
Scotland Yard have also formally identified residents Ya-Haddy Sisi Saye, also known as Khadija Saye, 24, Abufars Ibrahim, 39, Anthony Disson, 65, and Mohammad Alhajali, 23, as among the victims.
The rest are missing, presumed dead, Metropolitan Police Commander Stuart Cundy said on Monday.
In a statement, the family of Mr Disson said: ‘Our family are devastated at receiving the news that Tony sadly did not survive the fire at Grenfell Tower.
‘Tony leaves behind a large family, his wife, sons and grandchildren, including one grandchild he will never get to meet.
‘We miss him terribly, and are pulling together as a family and trying to stay strong under these tragic circumstances.
‘We ask at this time that our family are left to grieve in private.’
There were emotional scenes at the site in north Kensington at 11am as firefighters halted work to join residents for a minute’s silence held to remember those who lost their lives and all others affected by the blaze.
The silence was also observed at government buildings across the country.
Mr Cundy said the death toll may still change, but not as significantly as it has in recent days, adding ‘the awful reality is that we may not be able to identify all those that died’ inside what is now a blackened and charred shell.
He fought back tears as he told reporters at New Scotland Yard about the scene inside the tower.
Footage from inside the gutted building has been released, showing the extent of the damage.
Mr Cundy said it had been ‘incredibly emotional working in there’, adding: ‘On Saturday I went in myself and went to the top floor.
‘And it is incredibly hard to describe the devastation in some parts of that building.’
Speaking later outside Scotland Yard, he added: ‘I have investigated major crime for most of my service and I have seen some terrible things.
‘But I don’t think anything prepared me for what I was going to see when I was in there.
‘It’s hard to describe my feelings, because I cannot imagine, and I would not want to put myself in the position of those families who have lost their loved ones.
‘But being with colleagues from the London Fire Brigade when I was in there, colleagues from the London Ambulance Service and other police officers, I think it’s fair to say it is incredibly emotional working in there.
‘But we will do it with our utmost professionalism and we will do everything we can as quickly as we can to locate everybody who is in there.’
Five people who had been reported missing after the disaster have been found safe and well, he added.
Amid anger in the wake of the disaster, which was described by London mayor Sadiq Khan as a ‘preventable accident’, the Government announced that those left homeless will be given at least £5,500 from an emergency fund.