At least 16 people were killed and nine others injured as a blast took place in a passenger bus on Monday mooring in Kohat, northwest Pakistan, police said.

The blast occurred on Hangu road in Kohat in Khyber-Pakhtunkhwa province. Police said that at least 16 people were killed.

The bus was completely destroyed in the blast. According to local TV channels reports nearly 18 people were on board the bus.

There were conflicting reports about the nature of the blast. Leading private Geo television quoted police sources described the blast as suicide attack. ARY TV reported that the bomb attacked the coach near a check post at Juza area, some 10 kilometers from Hangu city. The report said that the attack may be aimed at targeting the security men at the check post.

State television earlier reported a gas cylinder caused the blast after the coach hit another vehicle.

The injured and killed were transferred to district hospital in Hangu where emergency had been declared by the authorities.

Security forces have cordoned off the area for precautionary measures.

Hangu is adjacent to lawless tribal belt of Pakistan, bordering Afghan border where American army is battling with local terrorists.

Last month 15 people were killed in the area when a suicide bomber rammed his explosive-laden bus into a hospital.