Security officials say militants have stormed a military checkpoint in northwest Pakistan, killing seven soldiers and wounding three.

Officials say 18 militants were killed when Pakistani forces retaliated during Friday's attack in the Kurram tribal agency.

At least four troops were said to be abducted by the Taliban, who claimed responsibility for the assault.

Friday's death toll could not be independently verified because the region is off-limits to journalists.

The incident was the latest in a series of deadly clashes between Pakistani security forces and militants in Kurram this week.

Pakistan's military first launched operations against Islamist militants in Kurram last July, and the fighting has yet to die down. It follows a series of similar military operations in the country's mountainous northwest aimed at stopping the Pakistani Taliban, known as the Tehrik-i-Taliban .

The TTP is responsible for many attacks targeting civilians, foreigners and government sites that have killed thousands during the past few years. The group says it wants to take down the Pakistani government, in part, because of its partnership with the United States in the war on terror.