LONDON (Reuters) - A 42-member team working to recover the remains of victims of the Grenfell tower apartment block fire in London are under huge emotional strain as they carry out a fingertip search of the gutted building, one of its leaders said.

Grenfell Tower, destroyed in a catastrophic fire, is seen from another area of the Royal Borough of Kensington and Chelsea, in London, Britain July 2, 2017. REUTERS/Peter Nicholls

At least 80 people are missing or presumed dead from Britain’s deadliest fire in decades which swept through the 24-storey housing block on June 14. London Police have confirmed that 255 residents survived the fire.

Police Sergeant Alistair Hutchins, one of two specialists leading the disaster victim identification (DVI) team which includes six archaeologists, said the task was psychologically arduous.

“We’ve never had an incident to this scale,” he said in a videoed interview released by London Metropolitan Police on Wednesday.

“The pressures it puts on you emotionally are huge. The DVI team are all volunteers and to ask them to enter a building like this and deal with the stuff they’re finding is a big task for them.”

Detective Superintendent Fiona McCormack, the officer in charge of the police investigation, told Reuters last month that officers were “many months from being able to provide a number that we believe accurately represents the total loss of life”.

Hutchins said the team were sifting through the debris to find the smallest human fragments from the fire which he said was the worst incident he had faced in his 18-year career in DIV.

“Those sieves are going down to a six mm size so that we guarantee that we can pick up small fragments of bone, teeth, any identifiable part of the human body we will pick up at that stage,” he said.

Hutchins also acknowledged the anger expressed by friends and relatives of the victims and those missing about the pace of the effort to locate and identify those who died in the fire.

“I understand how frustrating it is for people outside of this environment to sit there and wait and say, ‘well, why can’t I have my family back? Surely it’s easy.’ And it’s not.”