British Prime Minister Tony Blair will on Wednesday announce a timetable for the withdrawal of British troops from Iraq just as thousands of additional US troops were arriving there to try to restore order in Baghdad.
Blair, whose popularity at home has suffered greatly due to his support for the 2003 US-led invasion of Iraq, would make his announcement on Iraq troop deployments to parliament in the afternoon, a government source said.
He said Blair would say Britain's 7,100-strong Iraq force would fall to 5,500 by the end of the year. The Ministry of Defence was expected to flesh out the details on Thursday.
Media reports said the first troops could start leaving around the middle of this year.
Some newspapers said 3,000 soldiers could be home by the end of this year and one said all would be out of Iraq before 2009.
Blair, who is due to step down later this year, was expected to say the withdrawal reflected Britain's success in southern Iraq, where command of the main Iraqi army unit in Basra was handed over to Iraqis on Tuesday.
Blair's final months in office have been dogged by the unpopularity of the war in Iraq, where more than 100 British soldiers have been killed.
Since the 2003 invasion that toppled Saddam Hussein, British troops have been responsible for Iraq's southern-most four provinces, which are mainly Shi'ite and have been quieter than mixed or mainly Sunni areas patrolled by Americans.
In contrast to London, Washington is sending 21,500 more troops to Iraq as part of Bush's new strategy. There are currently more than 140,000 U.S. troops in Iraq.
Key-ally President Bush, who spoke to Blair on Tuesday, was upbeat about the British plans and hoped U.S. forces could follow suit when conditions allowed.
Bomb kills 11 in Najaf
"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," Gordon Johndroe, spokesman for the White House National Security Council, said.
"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," he said.
Australia, another staunch US ally, said it had no plans to reduce its 1,400-strong force in and around Iraq.
Iraqi Prime Minister Nouri al-Maliki has called the US-backed security crackdown in Baghdad which started last week a "brilliant success", but a series of car bombs that have killed scored has tempered early optimism.
A car bomb exploded at a police checkpoint near a busy market in the holy Shi'ite city of Najaf on Wednesday, killing 11 people, a doctor at a local hospital said.
The US military transferred Najaf province to Iraqi forces last December, although the city had been largely under Iraqi control for some time because of religious sensitivities.
Blair said on Sunday Britain would cut its force once Iraqis were responsible for security in Basra, Iraq's second-largest city and key center for oil exports.
He has said he will update parliament about the British mission in Iraq at the close of a four-month security operation in Basra -- Operation Sinbad -- which ended last week.
The British handed over security responsibility for two of their four provinces to Iraqis last year and abandoned their main base in a third. Its force is concentrated in Basra itself and at a nearby air base.