US military plans to send thousands of troops into southern Iraq in the event of a total British withdrawal have caused acute irritation in London.

The plans were disclosed by Lieutenant-General Raymond Odierno, the second-most-senior American commander in Iraq, in an interwiew with The Times earlier this week.

The timing of his remarks was viewed as particularly unfortunate, coming a few days after 500 British soldiers from the 4th Battalion The Rifles had withdrawn from Basra Palace, the last remaining British-controlled base in the city.

Although this was a highly symbolic move, the Government has been at pains to emphasise that it was not a precursor to a full-scale withdrawal of British troops from southern Iraq.

However, General Odierno’s comment seemed to underline the fears expressed by several US military figures recently that Britain was planning to withdraw prematurely, leaving the south to slide further into violence.

General Odierno said that the US had drawn up the contingency plan in case Gordon Brown decided to withdraw the total British force of 5,000 troops, indicating his belief that a general election was looming.

Defence sources in London said: “All we have done is withdraw from Basra Palace, which was agreed with the Americans and the Iraqis as a sensible move to allow the Iraqi security forces to take over responsibility for their own city in the south. But we’re not leaving Iraq.”

“Our commitment to Basra remains the same, and we are working to the same strategy as the Americans, except that we are doing things at a different pace and in different circumstances.”

The sources said that it made no sense for the Americans to feel that they needed to plan to reinforce the south if the British withdrew. One official said: “We’re not going to withdraw until the job is done, and when it is done, we won’t be leaving until everyone agrees, including the Americans and the Iraqi committee on national security, headed by the Iraqi Prime Minister.”

Major Mike Shearer, the British military spokesman in Basra, said: “From a military context we are absolutely in concert with our coalition partners. All we have done is reduce our operational footprint [by moving out of Basra Palace], but nothing else has changed; and since we withdrew from Basra Palace, the city has been quiet.”

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