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A MILITARY adviser to President George W Bush has warned that British forces will have to fight their way out of Iraq in an “ugly and embarrassing” retreat.

Stephen Biddle, who also advises the US commander in Iraq, said Iranian-backed Shi’ite militias in the south would try to create the impression they were forcing a retreat. “They want to make it clear they have forced the British out. That means they’ll use car bombs, ambushes, RPGs [rocket-propelled grenades] . . . and there will be a number of British casualties.”

The comments coincide with British military estimates that withdrawal could cost the lives of 10 to 15 soldiers.

Some British officers believe they are facing a “humiliating” retreat under fire to Kuwait or the southern Iraqi port of Umm Qasr.

“I regret to say that the Basra experience is set to become a major blunder in terms of military history,” said a senior officer. “The insurgents are calling the shots . . . and in a worst-case scenario will chase us out of southern Iraq.”

Gordon Brown, the prime minister, has agreed with Bush that no decision will be made to withdraw until after General David Petraeus, the US commander, delivers a report to Congress next month on the progress of the Americans’ “troop surge”.

But the British are expected to pull back to a single base at Basra airport soon in preparation for withdrawal.

Biddle, a senior fellow at the Council on Foreign Relations who advised Bush on the troop surge, said Iran would use its influence with the Shi’ite Mahdi Army to exploit the situation.

“It will be a hard withdrawal. They want the image of a British defeat . . . It will be ugly and embarrassing,” he said.

The Ministry of Defence said the British were not heading for defeat. “Although the militias are trying to claim credit for ‘driving us out’, they are failing.”

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