Two British newspapers reported in their Sunday editions that the pullout plan followed an acceptance by the two governments that the presence of foreign troops in Iraq was now a large obstacle to securing peace.
But a spokesman for the US military in Iraq reiterated previous statements by US and Iraqi officials that foreign troops would be gradually withdrawn once Iraqi security forces were capable of guaranteeing security.
Lieutenant-Colonel Barry Johnson said of the reports in the Sunday Telegraph and Sunday Mirror: "This news report on a withdrawal of forces within a set time frame is completely false.
"As we've said over and over again, any withdrawal will be linked to the ability of the Iraqi security forces to maintain domestic order on behalf of a representative Iraqi government that respects the rights of all its citizens. This is an ongoing assessment and not linked to any time frame."
"This news report on a withdrawal of forces within a set time frame is completely false"
Lieutenant-Colonel Barry Johnson, US military spokesman in Iraq
The newspaper reports quoted unnamed senior British Army sources confirming the pullout, saying London and Washington realised that staying in Iraq will inflame an increasingly volatile situation.
The only situation in which troops would stay would be if violence escalated into full-blown civil war, they said.
A Ministry of Defence spokesman in London rejected the reports, telling AFP that the British government had not altered its position set out by John Reid, the defence secretary, on 7 February.
Britain has about 8000 troops based mainly in Iraq's four southern provinces. The United States has about 136,000 military personnel posted around the country.
South Korean pullout
Meanwhile, South Korea's defence ministry announced on Sunday that it would begin bringing its troops home from Iraq next month under a plan to reduce its presence there by a third.
South Korea will begin pulling out
a third of its troops
South Korea plans to withdraw about 1000 of its 3200-member contingent stationed in northern Iraq this year.
The troop reduction will begin in April, said Major General Chung Seung-jo, chief of the Korean troops stationed in the Kurdish region of Irbil in northern Iraq, according to South Korea's Yonhap news agency.
South Korea's troop contribution has made the country the second-largest US coalition partner after Britain and Italy, which has the fourth-largest contingent in Iraq, has said it plans to pull out this year.
The Sunday Telegraph wrote: "The British government is understood to be the driving force behind the withdrawal plan, but all 24 coalition members are likely to welcome the move, given the growing international unpopularity of the war."
"The British government is understood to be the driving force behind the withdrawal plan but all 24 coalition members are likely to welcome the move, given the growing international unpopularity of the war"
Sunday Telegraph report
The Bush administration and Pentagon have stated repeatedly there is no timetable for withdrawing troops from Iraq, and a US military spokesman repeated that on Saturday. "We've made no such plans," Major Paul Swiergosz, a Pentagon spokesman, said.
US and Iraqi officials have said frequently in the past that foreign troops will be gradually withdrawn from Iraq once Iraqi security forces are capable of guaranteeing security for the 27 million population.
US and British troops have trained 230,000 Iraqis to take on roles in the police force and a slowly expanding Iraqi army, although both are still incapable of securing the country on their own.
According to the Sunday Mirror, the source told them: "We are rapidly approaching the time when there is simply nothing else for our boys and girls to do. We have trained 230,000 members of the Iraqi security forces. Remaining much longer will serve no purpose whatsoever.
The growing sectarian violence is
leading to more instability in Iraq
"In many cases, the appearance of British and US soldiers on the ground can inflame a situation. With the major training tasks completed all we represent are targets for the insurgents - inevitably leading to coalition deaths."
But an unnamed MoD official responded to the Sunday Mirror claims saying: "There is no question of us 'cutting and running'. If we get out it will be because all our conditions for withdrawal have been met."