Pakistan's military says at least three soldiers have been killed in clashes with Taliban militants in the troubled tribal region of Orakzai.
Security officials told the BBC that fighting started after the Taliban ambushed a military convoy.
At least 13 militants were also killed, the army says. There is no independent confirmation of the claims.
Meanwhile, police in the northern town of Bannu say they have arrested a German man leaving North Waziristan.
The man was taken into custody on Monday along with three others after they were discovered on a public bus coming out of North Waziristan, reports said. All were wearing burkas, the all-covering garment for women.
North Waziristan is seen as safe haven for al-Qaeda and Taliban militants, including some foreigners. Several foreigners have been arrested trying to go in or out of the area in recent years.
The Orakzai region has been the scene of several search operations by Pakistani security forces in recent weeks.
Taliban militants, fleeing army operations in the other parts of the tribal belt, have been trying to establish safe havens in the area.
"Militants used rockets to attack the convoy in the Kasha area of lower Orakzai," a military spokesman told the BBC.
"Three soldiers were killed and five injured when their vehicle was struck."
Security forces retaliated with heavy weapons, the official said.
"As a result 13 militants were killed and dozens were injured."
Locals said the convoy was on its way to the city of Kohat from Kalia, the main town of lower Orakzai.
The attacks come a month after the government said the area had been cleared of militants.
Since then there have been a number of militant attacks on security convoys in the region. Several soldiers have been killed.
Locals say security forces have managed to clear only the main roads and towns in the region, which is close to Afghanistan.
They say the Taliban still control the hills and forests in the area.
The attack comes days after more than 30 Pakistani soldiers went missing presumed captured by the Afghan Taliban after an attack on their border post in the nearby tribal region of Mohmand.