Pakistan has closed the Khyber Pass - the main supply route for NATO and American forces in Afghanistan.
A curfew is in force and the main road leading to the Afghan border is sealed.
Government troops have launched attacks against Taliban fighters in the region.
There have been a number of attacks in recent months aimed at stopping supplies being trucked through northwest Pakistan from the port of Karachi to NATO forces in Afghanistan.
The Khyber Pass runs between the northwestern city of Peshawar and the border town of Torkham.
The US Defense Department says 75% of its military supplies for the Afghan war are sent through Pakistan, including 40% of the fuel for US troops.
