Pakistani military officials say a roadside explosion in a semi-autonomous tribal region along the border with Afghanistan has wounded at least four Pakistani troops.
The officials say the bomb went off early Tuesday in North Waziristan as a military vehicle was traveling on the outskirts of Miran Shah, the region's main town.
No one has claimed responsibility for the attack and authorities are investigating.
Pakistan, a key anti-terrorism ally of the United States, has been trying to flush out foreign militants from the region for the past 15 months. The area is considered a possible hideout for al-Qaida leader Osama bin Laden.