The soldiers' compound has come under attack

Mr Hoon was asked by MPs about the controversial decision to deploy the UK troops into a US-controlled area in the south of Iraq.

He said the Black Watch were there to "maintain stability in a particular defined area".

On Monday the Black Watch were attacked at their base 25km south of Baghdad for the third time in four days.

Stability

Prime Minister Tony Blair has previously said the troops will be home by Christmas.

Mr Hoon told MPs: "The Black Watch achieved full operational capability today.

The war was based on two lies Stephen Hawking

"I am confident they will be back in their base in 30 days."

He added: "Essentially their job is to maintain stability in a particular, defined area. Precisely what they have been doing in the south."

Future concerns

On Monday six mortar rounds landed in the 850-strong battle group's base, Camp Dogwood, 16 miles (25km) south of the Iraqi capital. There were no casualties.

Downing Street has said such attacks were "expected" ahead of January's election.

The battle group is led by three companies of armoured infantry from the 1st Battalion The Black Watch, with some 500 men and 50 Warrior armoured fighting vehicles.

They are accompanied by a reconnaissance unit from the mainly Welsh Queen's Dragoon Guards, with around 100 men and 12 Scimitar armoured vehicles, and a 50-strong Royal Marine light infantry unit from 40 Commando.

Support troops include engineers, logisticians, signallers and medics.

As Mr Hoon was giving evidence to the defence committee, scientist Stephen Hawking branded the death of 100,000 people in Iraq a "war crime".

'Tragedy'

The author of a Brief History of Time told a rally in Trafalgar Square organised by CND and the Stop the War Coalition: "The war was based on two lies.

"The first was we were in danger of weapons of mass destruction and the second was that Iraq was some how to blame for 11 September.

"It has been a tragedy for all the families that have lost members.

"As many as 100,000 people have died, half of them women and children. If that not a war crime what is?"