In continuing wave of violence in Pakistan's northwest, a suicide car bomber blew himself up at a police check post on the outskirts of Peshawar on Saturday, killing at least five persons and wounding over 25 others.

The bomber detonated his vehicle packed with 50 kg of explosives when he was flagged at the checkpoint at Pishtakhara Chowk, the main entry point to Peshawar from the troubled Khyber tribal region.

The powerful blast blew a number of other vehicles lined up for the checking. A large number of people were present at a nearby bus terminus and commercial area when the blast occurred at about 4.15 pm.

At least five persons were killed and over 25 injured, district administration chief Shahibzada Anees told reporters. Peshawar, on the edge of Pakistan's tribal belt infested with al Qaeda and Taliban fighters, has increasingly become the favourite target for attacks by militants, particularly since the army launched its offensive on their stronghold.

The bomber came in a car from the direction of Bara, a town in Khyber Agency, and blew himself up when police were checking his vehicle, he said.

Security forces cordoned off the area as ambulances took bodies and the injured to three nearby hospitals. Several security personnel were among the injured. An emergency was declared in all hospitals across Peshawar.