Almost 400 prisoners escaped from a Pakistani prison after it was attacked by militants, officials have said.Dozens of Islamist militants armed with guns and rocket-propelled grenades launched the assault on the jail in north-west Pakistan at around 01:00 local time the BBC reported.

Officials said some of the freed inmates were themselves militants.

The jail is located in Bannu, a town in Khyber Pakhtunkhwa, which borders Pakistan's volatile tribal areas.

Pakistan's Taliban said they carried out the attack, but the claim has not been verified.

"We have freed hundreds of our comrades in Bannu in this attack. Several of our people have reached their destinations, others are on their way," a Taliban spokesman told the news agency.

Senior Bannu police official Iftikhar Khan told AFP that three police officers were wounded in the two-hour attack.

Officials described how militants in cars and pick-up trucks entered the complex shooting and throwing grenades.

A total of 381 were released out of nearly 1,000 in the prison, they said.

At least 20 of the prisoners were described as "very dangerous". Police say they include Adnan Rashid, a former member of the airforce sentenced to death for an attack on former President Pervez Musharraf.

The BBC's Aleem Maqbool in Islamabad says the attack is clearly a setback for Pakistan's security forces, who over the last year have gained considerable ground against militants in the northwest of the country.(BBC)