At least six people have been killed and three others injured after two roadside bomb blasts hit a passenger van and motorbike in the restive northwest, officials have said.

"The incident occurred in Chinori village of the Mohmand tribal district [about 120km northwest of Peshawar], the target was the son of a peace committee chief," said a local administration official on Friday.

Khushal Khan, a senior administration official, confirmed the incident.

"The first blast hit the motorbike, killing the son of the anti-Taliban peace militia and injuring his friend, while the second blast hit a passenger van killing five people," Khan told the AFP news agency.

Jamat-ul-Ahrar, a faction of the Pakistani Taliban, claimed responsibility.

"Tehreek-e-Taliban Pakistan Jamaat-ul-Ahrar accepts the responsibility of this attack, this attack was carried out to avenge the tyranny and humiliation that have been enforced upon oppressed Muslims by these apostate thugs," spokesman Ehsanullah Ehsan said in a statement emailed to the media.

Pakistan has been fighting off armed groups since 2004, after its military entered the region to search for al-Qaeda fighters who had fled across the border following the US-led invasion of Afghanistan.

The army launched an offensive against the armed groups hideouts in the North Waziristan tribal area, after a bloody raid on Karachi Airport in June.

Pakistan's army says it has killed more than 1,000 fighters and lost 86 soldiers since the start of the operation. The Taliban says the figure is far lower.

Source: Agencies