A blast on a bus carrying government employees in northwest Pakistan has killed at least 17 people, police offiicals say.

More than 40 people were also wounded in the blast in Peshawar on Friday, officials said.

"The bomb was planted inside the bus. At the moment, the death of 17 people have been confirmed while 47 were wounded," Zahirul Islam, deputy commissioner of the Khyber-Pakhtunkhwa provincial capital, told AFP.

Senior police official Rahim Shah confirmed that the bomb was planted inside the passenger bus, which was taking government staff home to the town of Charsadda after work.

Rescue teams rushed to the area, and the wounded were shifted to the Lady Reading and Charsadda District Headquarters hospitals, local media reported.

Television footage showed the back of the bus reduced to a tangle of twisted metal by the force of the explosion.

Peshawar has seen numerous gun and bomb attacks in recent years, carried out by the Tehreek-e-Taliban Pakistan and other armed anti-state groups.

On Sunday, a double suicide bombing at a church in the city killed at least 78 people.