Two attacks against British troops in Basra left one soldier dead and ten wounded yesterday, dealing a serious blow to hopes of bringing home thousands of troops within the next few months.

Two of the wounded were in a serious condition and one was in critical.

Although ministers have refrained from giving a withdrawal timetable, expectations have been raised that several thousand could be pulled out by the spring or early summer.

Senior defence sources said that the two attacks, on what was a “bad and tough day” for the British military, would not change the Government’s strategy. A cutback in numbers, they said, depended entirely on conditions on the ground and the ability of the Iraqi forces to take charge of Basra’s security.

The Catch-22 for the Government is that if conditions deteriorate, withdrawing any of the 7,500 troops will be difficult.

In one of the bloodiest recent encounters, a Land Rover on patrol south of Basra was caught by a roadside bomb. The armoured vehicle, which offers limited protection against high explosives, was blown off the road. One soldier was killed and three wounded, one critically. British troops sealed off the area and a helicopter helped to evacuate the injured to the main field hospital at Basra airport.

At almost exactly the same time, in an apparently coordinated assault, a mortar or rocket exploded in Britain’s base in Basra. A spokesman said that seven troops were injured, two “very seriously”, as well as an Iraqi employee.

The Basra base comes under almost daily attack, and commanders had been expecting a missile or rocket to be fired by the end of the week. The base is protected heavily by concrete blast walls and sandbags. It is rare for so many troops to be hurt by a single explosion.

American and British officials suspect that Iran has been assisting local Shia Muslim militants by arming, training and funding their operations against British forces.

There are plans to reduce the size of the British contingent inside the city and to move most of the troops to the large base outside Basra at the international airport. But there are fears that pro-Iranian groups will try to seize Basra and nearby oil resources.