Peshawar: A pickup truck packed with explosives blew up a security checkpoint yesterday in northwestern Pakistan, killing at least 17 people and injuring 80 in an attack possibly intended for a more important target, officials said.

About 170 km away in the volatile region, 24 people were killed after residents of villages tired of a "reign of terror" by Islamist militants foiled a militant kidnap attempt, then were attacked, the military said.

Television footage showed a blast crater one metre deep and destroyed vehicles and pieces of debris scattered across a large area. Officials said many people were trapped under the rubble of damaged buildings in a nearby market. Civilians dug frantically with their hands in hopes of finding survivors.

Nasirulmulk Bangash, a top police official in the area, said the vehicle carried at least 150kg of explosives - an amount he called "unprecedented" - and was apparently en route to Peshawar, the capital of the North West Frontier Province.

The amount of explosives indicated the attack was aimed at a higher-value target than the small checkpoint, but might have been tripped up by high security on election day, Bangash said, without speculating on what the intended target might have been.

At least 17 people died and about 80 were wounded, including 15 who were in critical condition, said Sahib Gul, an official at Lady Reading Hospital in Peshawar.

No claim

Several of the dead were believed to be police manning the post.

Sher Zaman, 15, told The Associated Press from a hospital bed that he was selling fruit from a cart at the market when he heard a large explosion and was knocked down when something hit him in the chest. He said residents quickly gathered and helped transport casualties to hospitals.

No one immediately claimed responsibility for Saturday's blast.