The investigations at Grenfell Tower have led police in London to believe the "number of people missing, but as yet unaccounted for" has risen from 58, the Metropolitan Police said.
Releasing the first images and footage (below) from inside the burnt-out building, Commander Stuart Cundy said some of the victims may never be identified.
He said: "The conditions due to the fire damage verge on indescribable, which is why this will be such a lengthy operation taking weeks to complete.
"We must also prepare people for the terrible reality that some people may not be identified due to the intensity of the fire."
Mr Cundy added: "Sadly that work leads me to believe that the number of people missing, but as yet unaccounted for has risen from yesterday's figure of 58."
An update on the figures is due to be released tomorrow.
Meanwhile, the fire was a "preventable accident" following "years of neglect" by successive governments, London Mayor Sadiq Khan said as the council chief leading the response to the crisis defended the relief effort.
Mr Khan said the local community was "frustrated" and "angry" in the wake of the blaze, which left at least 58 people feared dead, after he attended a church service near the tower block in west London.
His remarks came as Nick Paget-Brown, the Tory leader of Kensington and Chelsea council, insisted officials were on the ground "very soon" after the fire broke out following criticism from British Prime Minister Theresa May, who said the support given to residents was "not good enough".
Mr Paget-Brown also sidestepped questions over whether he felt guilty about the tragedy, telling BBC Radio 4's The World At One: "I feel terrible about the whole position we find ourselves in. All I'm keen to say is there is an effective, co-ordinated relief effort on the ground and I'm sorry if people haven't seen that."
Speaking outside St Clement's Church, Mr Khan said: "There is a feeling from the community that they have been treated badly because some of them are poor.
"The tragedy we're seeing is because of the consequences of mistakes and neglect from politicians, from the council and from the government."
Mrs May, who met victims at 10 Downing Street yesterday, has ordered more boots on the ground at the scene after labelling the support given to families in the aftermath of the tragedy "not good enough".
The PM, who "welled up" after hearing harrowing accounts from people caught up in the fire, said there had been "huge frustrations" on the ground as people struggled to find information.
She added: "I have ordered that more staff be deployed across the area, wearing high-visibility clothing, so they can easily be found, dispense advice and ensure the right support is provided."
Meanwhile, a company involved in the renovation of the tower was forced to deny cladding on the building was banned in the UK after comments made by Chancellor Phillip Hammond.
It was reported that the material used in the cladding covering Grenfell was Reynobond PE - a cheaper, more flammable version of two available options.
Appearing on the BBC's Andrew Marr Show, Mr Hammond said: "My understanding is the cladding in question, this flammable cladding - which is banned in Europe and the US - is also banned here."
John Cowley, managing director of CEP Architectural Facades, which produced rainscreen panels and windows for Grenfell Tower's cladding sub-contractor Harley Facades Ltd, said: "Reynobond PE is not banned in the UK.
"Current building regulations allow its use in both low-rise and high-rise structures.
"The key question now is whether the overall design of the building's complete exterior was properly tested and subsequently signed off by the relevant authorities including the fire officer, building compliance officer and architect before commencement of the project."
Father's Day cards were among the tributes left close to the charred remains of the tower today, as firefighters leaving the scene were greeted by cheers and applause from the local community.
Senior civil servants have been called in to deal with the aftermath of the fire amid criticism of the way the crisis has been handled by Kensington and Chelsea council.
NHS England said 18 patients remain in hospital after the fire, including nine who are in critical care.
At 58 casualties, the Grenfell Tower blaze is likely to be the deadliest in the capital since the Second World War.
The British Home Office said it is "making arrangements" for the family of 23-year-old Syrian refugee Mohammad Alhajali - the first victim to be formally identified - to travel to the UK for his funeral.