Gunmen in a car shot dead four policemen at a checkpoint in a restive northwestern Pakistani city on Sunday, officials said.

The shooting took place in Peshawar, capital of Khyber Pakhtunkhwa province, where Taliban militants are active.

"At least four policemen embraced martyrdom after unknown gunmen in a car fired at them when asked to stop for checking," senior police official Mohammad Ismail told AFP.

Nobody immediately claimed responsibility, but Taliban militants, who have been waging a bloody insurgency against the state, routinely target police and security forces.

A recent wave of bombings in Peshawar has killed more than 140 people.