Far from leaving the south of the country to Iraqi forces, the Americans are planning to fill any gap created by a British pullout of all its troops, top US officials say.

Up to 3,000 American troops would be deployed to the south, with a brigade or divisional headquarters established either at the Basra air station – where the bulk of the British force is located – or at a huge logistics camp at Shaibah, south of the city.

This would be seen as confirmation of what many regard as already a reality: that the Americans have been replacing the British in Basra since April, when the Iraqi Prime Minister turned to the United States rather than to Britain for his attack on Shia militia extremists there.

Up to 900 American troops from the US Marine Corps and the 82nd Airborne Division who were embedded with the Iraqi Army in Baghdad were deployed to Basra, along with thousands of Iraqi soldiers, to drive out the extremists.

Most of the Americans have stayed in Basra and the south because, as a US official told The Times, it was now accepted that Britain was going to pull out of Iraq.

Hundreds of US instructors are working with the Iraqi forces in Basra. There is a US air force base at Tallil, in Dhiqar province, and American troops are in Nasiriyah, also in the southwest.

The US official said that whenever American forces started to “draw down”, they would have to be withdrawn through Kuwait and it would be crucial to have US units based in the south to facilitate the process.

“We already have headquarters in the southern regions but there will probably need to be an extra headquarters established in Basra. Whether it will be a brigade or a divisional HQ is not yet decided,” the senior official said.

Times Recommends

• LA profits from Michael Jackson stimulus
• Berlusconi's absent wife causes G8 headache
• Chimps that took a punishing step for Man