Tony Blair and George W Bush have given a tough response to the anti-war protests staged across the world.

Bush's foreign policy advisor, Condoleeza Rice, said a decision on war was "weeks not months away" and delays would play into the hands of Saddam.

In the UK, Cabinet ministers rallied around the prime minister at Labour's spring conference in Glasgow with John Prescott urging grassroots activists to trust Blair.

Margaret Beckett, the environment secretary, used a radio interview to admit that there were "enormous political dangers" to the government and the Labour Party over Blair's stance.

"Of course, there is that danger and no one is more conscious of that than the prime minister and the cabinet," she said.

Downing Street said the prime minister was determined to push on with his strategy, knowing he has two weeks to find a second UN resolution that he hopes will turn public opinion around.

The Stop the War Coalition is calling for another mass demonstration for the first Saturday after any war on Iraq is declared.

Scotland Yard admitted that its estimate of 750,000 protestors had been taken while marchers were still making their way through Piccadilly and did not dispute that more than a million people had taken part.

"It's not an exact science," said a spokesman.