The prime minister yesterday gave the clearest hint yet that most British forces will be withdrawn from Iraq next year as he announced that their work was nearing completion.

Visiting Baghdad and Basra, Gordon Brown said he was ready to “reduce troop numbers” and announced a four-stage plan to bring them home.

A spokesman for Nouri al-Maliki, the Iraqi prime minister, confirmed that the final withdrawal could come “within a year”.

A wider initiative is under way to draw up conditions for the departure of all foreign troops from Iraqi soil and end the five-year occupation.

This weekend President George W Bush spoke for the first time of a “general time horizon” for withdrawal.

Barack Obama, the Democratic presidential candidate, has said he would order a 16-month timetable for pulling out most US combat troops.

Yesterday Brown, who arrived in Baghdad’s green zone for talks with Iraqi leaders aboard a military Puma helicopter, would not give a precise timetable for the withdrawal of the 4,100 remaining British troops there, despite his pledge last year to reduce troops to 2,500 in the first half of 2008.

“In a period of six months enormous progress has been made. It is certainly our intention that we reduce troop numbers,” he said.

Later, meeting British forces in Basra, the prime minister gave a clearer sign that their mission was almost over.

“We are now working with the Iraqi forces to train them up so that they can take over responsibilities so we can complete our work here in bringing Basra democracy, security and prosperity,” he said.

The prime minister set out four conditions for withdrawal, with the key milestone the successful holding of provincial elections next spring.

The other three conditions are: the completion of training of 30,000 troops and 20,000 police, progress towards economic reconstruction and the transfer to civilian control of Basra airport – the site of the British military base.

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