Pakistani military officials say four soldiers and 14 militants were killed as the army launched a ground offensive in a restive valley in the northwest.

The officials say five soldiers were also wounded in Friday's operation in the Tirah Valley in the Khyber tribal area. The officials spoke on condition of anonymity because they were not authorized to talk to the media.

Rival militant groups, including the Pakistani Taliban, have been fighting for supremacy in the valley in recent weeks, forcing thousands of civilians to flee the rugged, mountainous area.

Khyber is part of Pakistan's semiautonomous tribal region bordering Afghanistan, the main sanctuary for Taliban militants and their allies in the country. The army has launched many operations against the Taliban in Khyber and other parts of the tribal region.