At least 20 people were killed when a suicide bomber rammed an explosives-laden vehicle into a military checkpoint in Pakistan's troubled northwest, officials said.
The checkpoint is near the Orakzai tribal region, which has emerged in recent months as a major base for Taliban militants waging war on the Pakistan government.
The explosion wrecked a building housing troops and police next to the checkpoint, said Farid Khan, a senior police official in the nearby town of Hangu.
At least 18 members of the security forces as well as two civilians died, Khan said. More than a dozen other people were wounded, including the local police chief, other officials said.
Western nations are pressing Pakistan to take tougher action against Taliban and al-Qaida strongholds in the tribal belt along the Afghan border.
Militants most frequently attack security forces in the northwest. However, recent attacks, including assaults on the Sri Lanka cricket team and a police academy in the eastern city of Lahore, have fanned fears that their reach is spreading across the country.
An apparent US missile strike reportedly killed 14 suspected militants in Orakzai on April 1, the first such attack in the area since the CIA escalated attacks from unmanned aircraft last year.