We'll be out by 2008, British military chiefs tell the Iraqis

The timetable is set out in an official letter to the Iraqi government in Baghdad, the Daily Mail has learned.

It would see the last two UK bases at Basra Palace and Basra Airport handed over to local control before Christmas.

The plan represents a far faster withdrawal than expected and will put British ministers on a collision course with Washington, where the UK's presence as a loyal ally in the controversial war in Iraq remains highly valued.

Without the British military camp at Basra Airport - which currently acts as the main barracks and vital secure transport hub - it would be virtually impossible to maintain any significant UK force amid the violent turmoil of southern Iraq.

The planned withdrawal from the base will therefore mark a major watershed, heralding an end to Britain's responsibility for security in the war-torn and volatile Basra province.

While a few troops might stay on to continue training Iraqi forces, Britain's mission in Iraq will be largely brought to an end.

Troop numbers have already been reduced sharply in recent weeks from 7,000 to 5,500.

Most UK bases in and around Basra have also closed recently. The only remaining camps are at Basra Palace, one of Saddam Hussein's ostentatious

official homes which still houses the British Consul General, and the airport on the western edge of the city which has been the main UK headquarters since 2003.

The letter sent to the Iraqi government says a small British presence would remain at the airport, including technicians to oversee essential air traffic control systems.

But crucially British troops would no longer man checkpoints or guard the perimeter.

The seven-month hand- over timetable marks a significant departure from the Government's official position to date - that British troops will stay as long as Iraq's political leaders want them.

It reflects the intense pressure on the overstretched UK military of fighting simultaneous wars in Iraq and Afghanistan, and concerns that troops in Basra are achieving little.

In October the head of the Army, General Sir Richard Dannatt, told the Mail that Britain should leave Iraq 'some time soon because our presence exacerbates the security situation'.

British troops now expect to be attacked every time they venture on to the streets in Basra, and 15 have been killed in the last two months.

A debate is continuing among military chiefs and senior Whitehall officials over whether Britain's main military effort should lie in Iraq or Afghanistan.

Some argue there is more prospect of success against the

Taliban in Afghanistan, while others insist stabilising Iraq is of greater strategic importance, even if the operation there is more unpopular and difficult.

The plan to shut remaining Basra bases suggests those favouring a switch to Afghanistan have the upper hand.

One senior Army insider told the Mail: 'What Dannatt said last year was right then, and it's still right now.

It's a question of when we leave, not if, so why hang on? From what I can see much of the discussion is about how to present this as some kind of success.'

Leaving Basra with rival Shia militia factions fighting for control - and with continuing interference from Iranian elements across the border - will leave British ministers open to charges of an ignominious retreat.

Yesterday the Ministry of Defence played down talk of a definite timetable for withdrawal, insisting planners were looking at all contingencies.

A spokesman said: "Our policy on withdrawal from Iraq has not changed.

"Military planners routinely look at a range of options, and as we have always said, any withdrawal requires the conditions on the ground to be right."

But with troop levels rising in Afghanistan, Gordon Brown will be under pressure to make an early announcement on Britain's commitment to Iraq when he moves into Number 10 at the end of this month.

A total of 149 British servicemen and women have lost their lives in Iraq since the 2003 invasion began. Of those, 115 have been killed by enemy action.