BRITISH troops are to start leaving Iraq in the next few weeks, Prime Minister Tony Blair was expected to announce today.

Reports suggested that 1,500 men and women from Britain's 7,200-strong force could be withdrawn in April, with 3,000 pulled out by the end of the year.

Downing Street refused to confirm or deny the reports, saying only: "It is right that the Prime Minister should update Parliament first."

It is thought likely that Mr Blair will make any announcement in an oral statement to the Commons following his regular weekly grilling at Prime Minister's Questions.

He is expected to stress that any withdrawal will depend on the security situation on the ground.

Suggestions that he will set a 2008 target for the last UK soldier to come home are thought to be wide of the mark.

Troops reaching the end of their mission in the coming weeks are thought unlikely to be replaced.

Others will pull back into their heavily-fortified bases in preparation for their return home, handing over day-to-day responsibility for security to Iraqi forces.

Mr Blair told US President George Bush he agreed with Defence Secretary Des Browne that home-grown forces were now ready to take control and it was time for UK troops to start pulling out.

Mr Bush said Britain's troop cutbacks were a sign of success in Iraq.

US National Security Council spokesman Gordon Johndroe 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 give 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."

"We want to bring our troops homes as well. It's the model we want to emulate, to turn over more responsibilities to Iraqis and bring our troops home."

Mr Blair was today updating MPs on the completion of the six-month Operation Sinbad in and around the southern city of Basra.

The operation has seen UK and Iraqi troops going through Basra neighbourhood by neighbourhood, clearing out insurgent strongholds and supporting reconstruction projects ready for the handover of security responsibility to home-grown authorities.

The first sign that Iraqi authorities were taking responsibility for security came yesterday when an Iraqi army division based in Basra transferred from Coalition command to take its orders for the first time direct from an Iraqi headquarters in Baghdad.

* A US Marine was killed in fighting in the insurgent stronghold of Anbar province yesterday.

Anbar stretches west from Baghdad to the borders with Syria, Jordan and Saudi Arabia.

* At least eight people were killed and 31 wounded today when a suicide car bomber struck a police checkpoint in the Shiite holy city of Najaf. The blast came about 10.30am local time as a market area in the city, 100 miles south of Baghdad, was filled with shoppers.