The Government ignored warnings that a "vital window" to identify British victims was closing in the days after the tsunami disaster.
Families waiting for news now face agonising delays because ministers failed to respond to repeated offers of help from forensic specialists.
Details of a chaotic scramble to identify thousands of bodies in makeshift mortuaries began to emerge this weekend as British police said it may be months before relatives are told the worst.
Jack Straw, the Foreign Secretary, admitted on Friday that British relatives face "an agony of long uncertainty". But as Tony Blair prepares to make a statement to the Commons tomorrow on the disaster, his Government is being asked a growing number of questions over its response.
He will be pressed on why ministers failed to respond to increasingly urgent calls from forensic pathologists to act quickly. It emerged last night that the Government-backed Centre for International Forensic Assistance (CIFA) warned repeatedly that teams of British scientists should be dispatched to help with identification of bodies. Calls to Downing Street, the Foreign Office and the Home Office met with "deafening silence".
Tom Black, a director of CIFA, said: "They did have a narrow window in terms of the identification of Westerners which wasn't seized upon. We sent letters to the Foreign Office and Home Office and No 10 saying please act and act now. We had two emails back from low civil servants, a holding response.
"People who work in such fields know that in heat and water the identification window is very narrow. By not acting quickly the chance was missed. Vital time was lost."
CIFA specialises in human identification and was set up by Mr Black and his wife, Professor Sue Black, who heads the department of anatomy and forensic anthropology at Dundee University. Professor Black, the country's leading forensic scientist, has accused the Government of leaving Britain "internationally embarrassed" in its failure to use the forensic resources available in this country.
"Given the expertise that we have in the UK, it's extremely disappointing and enormously frustrating that we don't already have an appropriate forensic team on the ground," she said last week. The expert left for the disaster zone on New Year's Eve, engaged by a private company working for a number of other Western countries.
Dr Martin Evison, a forensic anthropologist at Sheffield University, who has worked on identification in Kosovo, said: "In a few months only skeletal remains will be discovered. When that happens you get incomplete bodies, are you going to DNA profile all the parts? "
A spokesman for the Foreign Office yesterday conceded that there were lessons to learn. "We did receive Professor Black's fax and it made valid points and it's something for us to look at in the future. It was forwarded to the Metropolitan Police. The decision by Her Majesty's Government to send police forensic teams was taken very quickly." He added that a team of 12 forensic identification experts had arrived in Colombo and Bangkok on 30 December, followed two days later by a team of 14, mostly from the Metropolitan Police.
"We were confronted by an open space with 1,000 bodies in row upon row upon row,", Detective Chief Inspector Graham Walker of the Met, who heads the British effort,told The Independent on Sunday yesterday. "We are talking weeks, possibly months. It's the scale of it. It's a war zone."
Another pathologist described the scene at Thailand's main mortuary as "mayhem", with teams from 19 countries working independently.
A spat between Thai and Chinese authorities over whether DNA testing could be carried out in laboratories in China has added to delays. It was also reported yesterday that hundreds of bodybags may have to be unzipped and fresh samples taken, after the ink ran on identification labels.
Michael Ancram, the shadow Foreign Secretary, has written to Mr Straw asking whether his department had "taken up all offers of expert forensic assistance".
His letter comes as relatives submitted a petition calling for more effective action by the Foreign Office to identify British victims' bodies.
Robert Brewster, returning from a trip to Thailand in an unsuccessful search for news of his son, Nicholas, is critical of the FO. "There were a lot of families walking around not knowing what to do."
Mr Straw announced on Friday that the likely death toll had risen to 441, with 50 confirmed dead, prompting speculation that the true figure had been suppressed while Mr Blair holidayed in Egypt. In fact, say Mr Straw's aides, the toll fluctuates "almost hourly". Nevertheless Mr Blair is expected to provide an updated figure to MPs tomorrow.
The official British death toll comprises 37 deaths in Thailand, 10 in Sri Lanka and three in the Maldives. Twelve days after the disaster, UN officials predicted the total number of dead would exceed 150,000. Britain's leading aid agencies have disclosed that donations by the public for the relief effort have now passed £122m - well over double the official £50m figure so far pledged by the Government.Reuse content