Devastation in Sri Lanka

Tony Blair has warned that many of the Britons missing since the Asian tsunami are likely to have died.

"Scores of British families are already coming to terms with the loss of loved ones, and many will fear the worst," he said at his monthly press conference on Thursday.

"As the hours and days go by, it is likely that many of those reported missing will also have died in those terrible minutes on Boxing Day.

"Our hearts go out to their families in their pain and grief."

By Wednesday morning it was thought that 41 Britons had died while about 159 were still missing.

The prime minister also continued to defend the government's handling of events since the tragedy first unfolded on Boxing Day.

He said the UK's call handling centre took some 40,000 calls on December 28, and had dealt with some 135,000 subsequently.

The Foreign Office has established temporary offices in all affected areas to help British nationals and work with local authorities, said Blair.

Police officers were also helping with the identification of British victims.

But the prime minister cautioned that even where bodies are found the process of identifying them was difficult and "would take time".

Family liaison officers were on hand to help the families of those who have died, he added.

There had also been a military response, with RAF planes helping to deliver aid and other vital supplies, and two navy ships providing logistical support.

"I'm sure that the pressures of these extreme circumstances will inevitably mean that not everything goes smoothly in every set of circumstances," said Blair.

"But that should not overshadow the continuing efforts of countless officials and volunteers, in conditions which are frankly impossible for us to imagine, to help those caught up in this disaster."