Islamabad  - At least six people were killed and eight more injured on Monday when an explosion ripped through a vehicle in north-western Pakistan, police said.

The blast took place when a pickup truck carrying passengers pulled into a filling station in Charsadda district of the restive North West Frontier Province.

"Six civilians, including two women and three children, were killed on the spot while eight others were wounded," local police chief Mohammad Riaz said.

The bomb was apparently planted in the vehicle.

Police feared the death toll could rise as two of the injured were in critical condition.

There was no immediate claim of responsibility for the blast that occurred on the border of Mohmand tribal district, where government forces are battling Taliban militants. (dpa)