Two suicide car bomb blasts killed at least 18 persons in Pakistan's northwest on Friday, police and witnesses said.

A bomber exploded his explosive-packed car near the office of spy agency ISI (Inter-Services Intelligence) in Peshawar, the capital of North West Frontier Province (NWFP), leaving 10 people dead and over 60 others injured.

The bomber succeeded to take his car to a check post near the ISI office in the highly-guarded area on Artillery Road. A witness said that soldiers at the check post signaled the car to stop but the bomber exploded the vehicle near the 3-storey building. He said the guards also fired at the car shortly before he detonated his bomb.

As a result of the blast, front structure of the spy agency's building was severely damaged. The blast was so powerful that dead bodies of the victims with stains of blood scattered in the area with black smoke fume over the sky. Windowpanes of nearby buildings at the vicinity were smashed into pieces.

Hospital sources said that soldiers and employees of ISI were among those killed and injured.

The spokesman of Lady Reading Hospital Sahib Gul said that several victims are in critical conditions while seven injured in precarious condition have been shifted to ICU.

District Coordination Officer (DCO) of Peshawar Sahibzada Anees said that rescue operation continued and debris of the building are being removed.

All schools and educational institutions in the area were closed, according to the authorities.

The security forces cordoned off the area and also pushed the TV cameramen and photographers away from the site. Private ambulance service was also not allowed by the soldiers to shift the injured to the hospital, an official said.

No group claimed responsibility for the attack. But such attacks are often blamed on Taliban-linked militants.

In another related incident, a male bomber exploded his explosive-laden car near a police station in Bannu district in the northwest, police said. At least six policemen and two civilians were killed and 22 others were injured in the attack at Bakakhel area. Head of the police station was among the injured.

The attack destroyed the building, witnesses said.