PESHAWAR: A bomb ripped through a Pakistani police station in the suburbs of the northwest city of Peshawar Monday, heavily damaging the building and killing three people, officials said.

It was the fifth bomb in just over a week to hit the sprawling city of 2.5 million people, which lies on the edge of Pakistan's lawless tribal belt, where the military is waging a major offensive against Taliban fighters.

"Three people were killed and more than 20 are injured," Sahib Zada Anis, head of the northwestern city's administration, told reporters.

Witnesses told AFP that a pick-up vehicle came towards the police station and exploded nearby, causing heavy damage to the building and also damaging a mosque and boys' college.

Police official Mohammad Karim Khan said the explosion was caused by a bomb, but there was no immediate confirmation on whether it was a suicide attack.

Much of the police station was in ruins and ambulances raced through the streets on the way to the site of the attack in Peshawar's heavily populated suburb of Budh Ber, an AFP reporter said.