At least 20 people were killed and several others injured on Saturday when a suicide bomber rammed his explosive-laden vehicle into a police station in Pakistan's restive northwestern Swat valley.

The attacker drove the vehicle into the police station at Charbagh, located about 10 km from Mingora, the main town of Swat district, on Saturday morning.

Paramilitary troops were also deployed at the police station in Charbagh, which has witnessed violent attacks by the militants in the recent past.

State-run PTV reported that 20 people were killed in the attack. Curfew was imposed in the region and the injured were rushed to nearby hospitals in private vehicles.

Muslim Khan, the Tehrik-e-Taliban Pakistan spokesman in Swat, claimed responsibility for the attack.  

The security forces are currently conducting operations against the local Taliban [Images] in the Swat valley of the North West Frontier Province.

Saturday's bombing was the third suicide attack in Pakistan since Tuesday, when 78 people were killed when a suicide bomber blew himself up in a hospital at Dera Ismail Khan city in the same province.

A total of 78 people were killed when three suicide bombers blew themselves up outside a ordnance factory complex in Wah cantonment, about 50 km from Islamabad [Images], on Thursday.

The Taliban claimed responsibility for the attacks in Dera Ismail Khan and Wah.