A force of around 4,000 British troops will stay behind in Iraq for an indefinite period, even after all provinces controlled by the UK are handed over to the Baghdad government in nine months' time, senior defence sources said yesterday.
The soldiers will be positioned at a base in Basra ready to act to "protect the investment" made by US and British forces in the country, it was disclosed.
A senior British commander said that it was "feasible" that the last British controlled region could be handed over to the Iraqi authorities by the middle of next year.
The province of Dhikar, run by the Italians, is also due to come under Iraqi control in the near future. The Independent has learnt that the Rome government plans to pull out the whole force of 2,700 within the next month as Italy takes the lead role in providing more than 3,000 troops for an international Lebanon force.
A senior Italian diplomat said: "The announcement about Dhikar is imminent. We are not going to have any troops on the ground in Iraq. We are undertaking a very difficult mission in Lebanon, and we also have more than 2,000 troops in Afghanistan at the Iranian border."
The size of the British forces to be left behind, more than half of just over 7,000 deployed in Iraq at present, will raise criticism that no exit strategy is in sight.
The revelation about the long-term deployment in Iraq came as the same officials warned that Britain was in for the "long haul" in Afghanistan.
But the message from senior officials yesterday was that the situation in Iraq remains far too dangerous for a full pull-out in the foreseeable future. They insisted that the remaining British forces would not be sent to US-controlled central Iraq to help deal with the fierce Sunni insurgency and the spiralling sectarian conflict.
However, a senior military commander said: "We anticipate there is not going to be a political appetite to say 'job done' while there is still unfinished business in the centre of the country.
"We started this as a coalition and we need to protect our investment. The wheels could start to come off in places like Basra if people are left prematurely without support."
The province of Muthanna has been officially handed back to the Iraqi government, and British troops are pulling out of their bases in Maysan. However, an example of how hazardous the situation remains on the ground came when British soldiers came under attack in the town of al-Amara yesterday. At least two Iraqis were reported killed in the ensuing firefight.
Basra, Iraq's second city, has been the scene of confrontations between British troops and local police, who have been heavily infiltrated by the Shia militias the Badr Brigade and the Mehdi Army, led by the radical Shia cleric Muqtada al-Sadr.
A senior defence source said: "There are rogue elements linked to people committing illicit killings, some of them alarmingly close to the government structure."
There was also continuing concern about Iranian influence. "The worry we have is the appearance of technology - improvised explosive devices - which appear to be pretty well identical to what we have seen Hizbollah use. We all know that Hizbollah has a very close relationship with some parts of the Iranian government."
n The US Marine Corps said yesterday it had been authorised to recall thousands of marines to active duty, mainly due to a shortage of volunteers for duty in Iraq and Afghanistan.
Up to 2,500 marines will be brought back at any one time, but there is no cap on the total number of marines who may be brought back into active service.
Marine Colonel Guy Stratton estimated that there was a current shortfall of about 1,200 marines needed to fill positions in upcoming deployments.
This is the first time that the US Marines have been authorised to use involuntary recall since the early days of the Iraq invasion.