Metropolitan Police deputy commissioner Craig Mackey told the London Assembly in an update on the complex probe into the last month's blaze that displaced hundreds that the fire crime scene in west London was comparable to the 9/11 attack in New York in 2001.
"The people we are taking advice from are some of the people who worked on 9/11 and the fall of the towers. It is an extraordinary size of crime scene and extraordinarily complex," he said.
So far 39 bodies have been identified, but Mackey suggested the remains of many others might never be recovered.
"Without wanting to be too graphic - but I hope it helps explain - the fire in some parts of that building burned at over 1,000C for a considerable period of time," he told Assembly members at City Hall in London.
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"So we are now working through floor by floor, and it is literally a case of sifting and working through the debris - sadly, the remains - to try to desperately identify parts of people so we can reunite [the remains with families].
A total of 60 companies and organisations are being investigated, including one organisation that has submitted 4 terabytes of data - the equivalent of 20 million boxes of A4 paper, he said.
Around 255 people are believed to have survived the blaze, which engulfed the 24-storey block in the early hours of June 14.
Meanwhile, the Kensington and Chelsea Council - in charge of the residential block - held a meeting chaired by its newly elected leader Councillor Elizabeth Campbellthis week where sheinvited victims, survivors and community groups who wished to speak to contribute.
"I am deeply sorry for the grief and trauma you are suffering. I am deeply sorry we did not do more to help you when you needed it the most," she said.
But residents used the meeting to express anger that some victims have not yet been buried or identified, as well as asking why survivors are still waiting to be rehoused.
The fractious meeting ended early after a female resident of Grenfell Tower fell to the ground and was attended to by medical professionals.