Mr Bush, who is due to arrive in Britain for the final leg of his European tour, said that there should be no "definitive timetable" for troop reductions.

His comments to The Observer followed a report last week suggesting the Prime Minister could make an announcement on the final pull out-of Britain's remaining 4,500 troops before the end of the year.

While the president said he had discussions with Mr Brown on the issue and that they both wanted to bring their forces home, he stressed this could only be "based upon success".

Asked about the possibility of a formal timetable for major reductions, he said: "Our answer is: there should be no definitive timetable."

He added: "I am confident that he, like me, will listen to our commanders to make sure that the sacrifices that have gone forward won't be unravelled by draw-downs that may not be warranted at this point in time.

"I look forward to discussing it with him."

Downing Street insisted that there was no disagreement with the US over the withdrawal of troops from Iraq.

A No 10 spokeswoman said that any draw-down UK forces would depend on "conditions on the ground".

"It is not our policy to set arbitrary timetables," she said.