The Pakistani military said at least three soldiers were killed and at least eight were missing after insurgents attacked a checkpoint overnight in the remote border region of North Waziristan.
More than 34 militants were also killed in the clash in the village of Datta Khel, the military said on November 16.
A curfew has been imposed in Datta Khel, where soldiers were combing the area around the Spara Gher checkpoint for the missing troops.
Since June the army has been engaged in an offensive to push the Taliban out of North Waziristan, a key insurgent stronghold.
Pakistani jets and artillery began hitting rebel targets in North Waziristan in mid-June and ground forces moved in on June 30.
The military says nearly 1,500 militants and 124 soldiers have been killed since the operation began.
The figures cannot be independently confirmed.