PESHAWAR  - Fifteen militants and one soldier were killed on Thursday when the Pakistani military mounted another operation in a week of fighting designed to seize control of the Tirah Valley, the army said.

The military has faced fierce resistance from the Taliban and its allies in the Khyber region since troops set out to dislodge insurgents from strategically important heights above the valley six days ago.

Military officials say insurgents use the valley as a base camp that enables them to carry out raids in other semi-autonomous tribal areas near the Afghan border.

“Fresh clashes started early Thursday when the security forces launched another operation to secure control of the valley,” said a military official in Peshawar, adding that 15 militants and a soldier had been killed.

On Tuesday, the military said 23 soldiers and 110 militants had been killed in four days of fierce fighting in the area. Since 2009, the military and pro-government militias have clawed back territory from the Taliban.