It is rare for Ministry of Defence insiders to confirm that their forces have been involved in skirmishes, but a source close to the SAS said there had been a clash late on Friday.

SAS troopers, together with members of MI6 and the CIA, are working with the anti-Taliban Northern Alliance in the search for Osama Bin Laden, the Saudi-born millionaire believed to have masterminded the suicide hijacker attacks on America 12 days ago in which 6,818 are feared to have died.