Black Watch soldiers are preparing to take control of trouble spots in the US-controlled sector of Iraq.

Defence secretary Geoff Hoon told MPs that the government and military chiefs had agreed to the American request to transfer 850 soldiers from the Basra region.

The Americans have accepted that British commanders will have total control over tactics.

The Cabinet unanimously approved the move after being told that an assessment for General Sir Michael Walker, the chief of the defence staff, showed there was "a compelling military operational justification" for doing so.

However, the Guardian reports that senior ministers engaged in an "intense" debate on the redeployment, with some expressing criticism of the way the announcement was handled.

The move also prompted criticism from Labour backbenchers.

Former minister John Denham said there would be a political cost to the redeployment that would "be borne in part by our political party, perhaps more importantly in the standing of this country abroad if the civilian deaths we fear turn out to be on a scale that people are worried about".