A roadside bomb killed at least three Pakistani security personnel in North Waziristan tribal region on Sunday, the military said in a statement.
It said an improvised explosive device went off while a bomb disposal team was undertaking routine search and clear operation in Ghulam Khan, a town bordering Afghanistan.
No group claimed the attack. Officials here usually blame militant groups for attacks on security forces.
Pakistani forces have cleared most of North Waziristan of all the militant groups following major operation launched in June 2014. Officials said most of the militants have either fled to Afghanistan and some may be hiding in the rugged mountains and carry out targeted attacks.
On December 12, gunmen fired at an army vehicle in North Waziristan and killed two security men including a senior officer, according the army.