He [Mr Blair] assured me that the force will in no way undermine Nato

George W Bush

And Mr Blair said that the force would merely complement Nato and not undermine it.

Mr Bush also said he was confident of persuading America's allies to accept his plans for a national missile defence system - the so-called "son of Star Wars".

He added that the two leaders would work together to make sanctions against Iraq more effective and build a consensus in the region.

The meeting was billed as informal

The meeting between Mr Bush and Mr Blair at the Maryland presidential retreat of Camp David was the president's first with a European leader since he took office.

The White House had billed the meeting as "informal" and a chance for the two leaders to get to know each other.

Fears have been expressed on both sides of the Atlantic that the European rapid reaction force, which is designed to deal with regional troublespots, would weaken Nato's role.

But Mr Bush offered something of an endorsement to the plan.

"I support his point of view," Mr Bush said of the British prime minister's advocacy of the force.

"He also assured me that the force will in no way undermine Nato. I think that makes a lot of sense."

Missile defence

Mr Blair described the force as "an additional string to our bow in circumstances where Nato does not want to be involved".

But he stopped short of backing Mr Bush's missile defence proposals.

He said only that he understood and shared US concerns about weapons of mass destruction and called for further discussion of ways of dealing with the threat.

Radars at Fylingdales would need updating

The US president, however, remained optimistic about persuading critics of the missile shield to support it.

"I don't think I'm going to fail to persuade people," he said.

"Son of Star Wars" is opposed by Russia and China, and several European countries have serious misgivings about it.

Mr Blair has refused to say whether he would agree to use of the British early warning base at Fylingdales for the shield, which critics say would make Britain a prime target for anyone wanting to strike the US.

But correspondents say based on Mr Blair's comments made earlier in the day that he is edging towards accepting the plan.