Bush said ahead of his historic visit that it was an "exciting" time for both to be leaders. But in many ways the American president's visit to London will be a test of the so-called "special relationship" between the trans-Atlantic allies.

Bush and Blair maintained a united front against reluctant allies before and during the Iraq war but now both are paying the price of the failure to find any weapons of mass destruction.

Tony Blair has defended George Bush's controversial state visit to Britain as a chance to reaffirm shared values.

He told the London tabloid News of the World the visit was an ideal time to celebrate freedom, security and a "better, more prosperous and peaceful future" for Iraq.

Anti-war campaigners have been fiercely critical of next week's trip, as violence in Iraq continues.

Lord Hattersley, former deputy Labour leader, said it was "propaganda" for Mr Bush's presidential election campaign.

Former foreign secretary Robin Cook, who stood down as Commons leader over the war in Iraq, said on Saturday the decision to give Mr Bush a full state visit was "baffling".

Mr Blair admitted George Bush's critics were "rubbing their hands at the scope for embarrassing him".

The prime minister said he himself has aired some differences with the US president, over such issues as global warming and steel tariffs.

"But I welcome this visit because it's more important than ever to underline that our two countries share the same values, the same love of freedom and determination to build a safer world," he said.

Speaking in an interview with Sir David Frost being broadcast on Sunday, President Bush gave a robust defence of the situation in Iraq and insisted terrorists would be defeated.

"They want to shake the will of the free world," he said. "The good news about having a partner like Tony Blair is he won't be shaken, and neither will I."

On Saturday the US-led coalition in Iraq announced a speeded-up transfer of power.