In a separate incident, the UK peacekeeping contingent in the capital Kabul sustained its first casualty when a soldier was shot and seriously injured while on patrol in a crime-ridden area of the city.

Lieutenant-Colonel Neal Peckham, the military spokesman for the UK-led International Security Assistance Force (Isaf), said a gun went off accidentally and the incident "did not involve any party outside of Isaf".

The injured soldier, who was treated at a local French hospital and then evacuated from Kabul, is reported to have been hit in the head by a single bullet.

The British troops have been tasked with patrolling the volatile and crime-ridden west of the city.

Armed robberies

In recent weeks, there have been a number of shooting incidents there.

The UK-led Isaf force is trying to maintain stability in Kabul

Three days ago, two rockets were fired at a barracks being used by the peacekeeping troops on the eastern edge of the city. No one was hurt.

The 18-nation peacekeeping force has been patrolling the area because of a wave of armed robberies blamed on unemployed Northern Alliance soldiers who fought against the Taleban.

The soldiers are thought to be mostly ethnic Tajiks from northern Afghanistan who have not been paid for months or given roles in the country's new security forces.