The foreign aid budget is being stretched by the demands of the tsunami disaster.

Tony Blair revealed yesterday that Britain's contribution will substantially exceed the £50 million already pledged.

This will mean that Hilary Benn, the international development secretary, will have to ask for extra cash from the Treasury to avoid cuts in other areas of his budget.

"The money we've pledged so far for the immediate response to the emergency will not come out of the normal aid programme... if we feel we need to make further contributions, we may need to go to the Treasury," said a Department for International Development official.

"We'll see where we are with the contingency fund."

The news came as millions of people across Europe yesterday marked a three minute silence to pay their respects to the victims of the tragedy.

Meanwhile, there was embarrassment for the government when Indonesia rejected the offer of 120 Gurkhas to assist the relief effort.

"What happened in Aceh is a pure humanitarian issue," a spokesman for the Indonesian embassy said.

"Indonesia does not want to make it look like a military issue. If the government wants to help, it should send doctors not troops."

The Daily Mail reports that the true figure of British dead in the disaster could be as high as 600.