British Royal Marines have been scouring mountains in southeast Afghanistan in a major new hunt for al-Qaeda and Taliban fighters.
The 1,000-strong force involved in "Operation Snipe" plan to destroy al-Qaeda caves and bunkers and to kill or capture any al-Qaeda militants or Taliban followers in the area, Brig Rodger Lane said.
"I can confirm that this is one of the few remaining areas that has never before been investigated by coalition ground forces and we have good reason to believe that it is or has been a key base for the al-Qaeda terrorist network," Brig Lane said.
"A potent force of around 1,000 strong and equipped with the full range of combat power at my disposal has been deployed by air and by land to first secure and then search a large and challenging area in what is a strategic key location for our enemy".
An Afghan Interior Ministry spokesman said hundreds of Kabul troops had also been moved to the area that was southeast of the town of Khost, about 140 miles south of the Afghan capital.
The operation is expected to last several days.