WASHINGTON - The United States yesterday put a brave face on plans by its closest ally, Britain, to start pulling its 7100 troops out of Iraq.

Under pressure domestically to show progress in the war and attacked in Congress for escalating US troop levels amid rising violence, the White House called the British withdrawal a positive sign after Prime Minister Tony Blair telephoned President George W. Bush to inform him of the move.

"President Bush sees this as a sign of success and what is possible for us once we help the Iraqis deal with the sectarian violence in Baghdad," said White House spokesman Gordon Johndroe.

"The President is grateful for the support of the British forces in the past and into the future. While the United Kingdom is maintaining a robust force in southern Iraq, we're pleased that conditions in Basra have improved sufficiently that they are able to transition more control to the Iraqis.

"The US shares the same goal of turning responsibility over to the Iraqi security forces and reducing the number of American troops in Iraq."

British newspapers said Blair was preparing to announce his withdrawal plan in Parliament.

They said some British soldiers could be brought home within weeks and all would be pulled out by the end of 2008.

The first contingent of 1500 troops could leave Iraq in a matter of weeks and another 1500 were likely to follow by the end of the year.

Australian Prime Minister John Howard has ruled out following Britain's lead and reducing troop numbers in Iraq. Australia has about 550 soldiers in southern Iraq and Howard says there are no plans to reduce those numbers.

In Washington, Democratic Senator and 2008 presidential hopeful Joseph Biden said the US should follow Blair's example and set a timetable for the withdrawal of US troops from Iraq.

"But while leaving Iraq is necessary, it doesn't answer the critical question: 'What next?' We need a plan for what we leave behind so that our interests are protected," Biden said.

"The heart of that plan must be a political settlement, one that gives Iraq's warring factions a way to share power peacefully and offers us a chance to leave with our interests intact."

In New York, the anti-war VoteVets.org group of veterans of the Iraq and Afghanistan conflicts called Blair's pullout plan an "abandonment of American policy in Iraq".

"Tony Blair was truly President Bush's last ally when it came to the war in Iraq and the failed strategy, and now even he has abandoned the President," said VoteVets chairman Jon Soltz.

"If Prime Minister Blair truly believed in the course we are on in Iraq, he would not pull out troops when US forces are severely overstretched.