UP to 800 soldiers from the region will be sent to war-torn Iraq within weeks despite an overall reduction in troop numbers, it was announced last night.

Defence Secretary John Reid ordered the deployment of the Devon and Dorset Light Infantry unit, stationed at Catterick Garrison, in North Yorkshire, to replace soldiers being brought home.

In the biggest British withdrawal from Iraq so far, Dr Reid said the total number of troops would fall by 800 to 7,000, because of the strengthening of Iraqi forces.

But the reshuffling of the hard-pressed Iraqi army means between 600 and 800 members of the 1st Battalion of the Devon and Dorset regiment will start their tour of duty in early May.

The deployment comes amid growing fears that, three years after the US-led invasion to remove Saddam Hussein, Iraq is sliding into a civil war.

More than 100 British soldiers have been killed since the war began and tension has grown since the publication last month of photos of troops appearing to abuse Iraqi civilians.

Accusations have been made of growing involvement by Iranian-backed militias in the police and security services in the south of Iraq, aggravating the insurgency.

Meanwhile, a frenzy of sectarian violence has followed the destruction of a holy Shia mosque a fortnight ago, including Sunday's attack on a Baghdad market that killed at least 58 people.

However, Dr Reid told MPs that only two per cent of violent incidents were in the southern provinces to which the British troops would be sent.

And he insisted civil war was "neither imminent nor inevitable", pointing to the calm reaction of senior Iraqi figures and its troops to the recent violence as encouraging signs.

In a statement, Dr Reid said there were now 235,000 members of the Iraqi security forces equipped and trained, with 5,000 more signing up every month.

However, the announcement was not part of the long-awaited handover of responsibility, because Iraqis were not yet ready for that.

A new committee of Iraqi ministers, military staff and coalition figures is to start assessing whether some provinces could begin the handover.

Dr Reid said it was the "end of the beginning" of British involvement in Iraq but he added: "The reductions I have announced are not part of a handover of security responsibility.

"They are not caused by, nor a cause of, changes in troop levels of other coalition allies."

He added: "Despite the ferocity of the terrorists, the Iraqi people will not be defeated - and our will to see the job done will not be broken."

But Conservative defence spokesman Gerald Howarth warned it would be "folly" to withdraw hastily before Iraqi forces could provide adequate security.

And he sought an assurance that the reduction was not motivated by the need to find additional troops to send to Afghanistan.

The number of UK troops in Afghanistan is expected to rise from 893 to 5,700, at a cost of £1bn.

Most are being sent to the volatile Helmand area in the south of the country.

Former Army officer Colonel Tim Collins also suggested the reduction sent out the wrong message and insisted the Iraqi army was in no condition to take over.

Colonel Collins told the BBC: "This is no time to give those trying to start a civil war any hope or succour."

Downing Street has always insisted there is no strict timetable for British troops to quit Iraq, because withdrawal depended on the "quality and quantity" of its own troops. The 1st Queen's Dragoon Guards and the 12th Regiment Royal Artillery are among other major units that will go to Iraq in May.