A British officer with extensive experience of Iraq said: "We are unlikely to up sticks and leave while America is still embroiled. We will maintain a presence alongside the US, albeit after we circle the wagons and go low-profile, to prevent other coalition members from leaving en masse."
The International Institute for Strategic Studies predicted that coalition troops would have to remain to underpin Iraq's fledgling democracy "well into the next US presidency".
The Republican-led Senate yesterday rejected a Democrat demand for George W Bush to submit an estimated timetable for withdrawing US forces.
By Ian Bruce, Defence Correspondent
BRITISH and American troops in Iraq plan to pull back into five or six super-bases away from the main cities, according to senior military sources.
The UK garrison of 8500 will be reduced to around 3000 and withdrawn to a fortified camp at Shaibah covering Basra's military airfield.
The move will take place as soon as Iraqi forces are deemed capable of providing basic security against insurgents. It will involve a phased pull-back from bases in outlying provinces, and will save the Ministry of Defence up to £500m a year. No timetable has yet been set.
Troops, on six-month tours of duty, would back up local forces in the event of a major insurrection or increased levels of insurgency. They would be strategically placed to crack down on infiltration by Shi'ite militants across the Iran border.
The US intends to drop troop levels from 138,000 to 92,000. However, planners say it could be 2010 before political and military factors allow this to happen.
Coalition officers said talk about mass withdrawals from the end of next year was "speculation without foundation", although some British units could begin the handover to Iraqi army units in two quieter provinces by late 2006.
However, any handover suffered a setback yesterday when it was revealed 173 Iraqis held at an interior ministry detention centre were found to be mistreated. They were malnourished, and some appeared to have been tortured.
They were discovered after US forces took control of the interior ministry building. The ministry is controlled by Shi'ites. Sunni leaders have accused the Shi'ite-dominated security forces of detaining, torturing and killing hundreds of Sunnis.
US Major General William G Webster said it would take "at least two years" for the Iraqi army to produce officers capable of exercising independent command and planning functions.
British troops have already curtailed all but essential patrols in and around Basra since two special forces' soldiers were held hostage by renegade police in September, and a rescue operation pro-voked a riot.
Senior MoD sources admitted yesterday the strategy of pulling back to bases away from major population centres was the one that would be pursued.
A British officer with extensive experience of Iraq said: "We are unlikely to up sticks and leave while America is still embroiled. We will maintain a presence alongside the US, albeit after we circle the wagons and go low-profile, to prevent other coalition members from leaving en masse."
The International Institute for Strategic Studies predicted that coalition troops would have to remain to underpin Iraq's fledgling democracy "well into the next US presidency".
The Republican-led Senate yesterday rejected a Democrat demand for George W Bush to submit an estimated timetable for withdrawing US forces.
The need for their presence was emphasised by the discovery of the mistreated detainees. The prime minister, Ibrahim al Jaafari, a Shi'ite, said Iraqi authorities were investigating. "I was informed that there were 173 detainees held at an interior ministry prison and they appear to be malnourished. There is also some talk that they were subjected to some kind of torture," he said.
A "deeply shocked" Jack Straw, foreign secretary, and Amnesty International welcomed his decision to order an investigation.
