Six Pakistani soldiers were killed and dozen others were injured on Saturday in a suicide car bomb attack.
The attack took place in Bannu city where the bomber targeted the camp office of the paramilitary Frontier Corps troops, who are deployed in militant-infested North Waziristan, which borders Afghanistan.
"The bomber drove his explosives-packed vehicle into the FC building," local police official Muhammad Shafiq told AFP.
He said the camp office was damaged in the attack.
Two local intelligence officials also confirmed the attack and feared the death toll could rise.
"There may be some more dead bodies lying under the debris of the single-storey building which was attacked from the back," they told AFP.
Senior local police official Feroz Shah said the death toll stood at six, from an initial toll of five killed and 12 wounded.
Bannu is 40 kilometerseast of Miranshah, the main town in North Waziristan.