A suspected US drone has carried out a rare missile strike in north-west Pakistan outside the country's remote tribal region, killing six people, including at least two Afghan militants.

The missiles hit an Islamic seminary in the Tall area of Hangu district in Khyber Pakhtunkhwa province, said police officer Fareedullah, who goes by one name, and intelligence officials. The six bodies were badly burned, he said.

It was one of the first drone attacks to occur outside Pakistan's tribal region along the Afghan border and could increase tension between Islamabad and Washington. Khyber Pakhtunkhwa province is considered a "settled area" of Pakistan, meaning it is generally more populated and developed than the tribal region.

It was also the first drone attack since the US killed former Pakistani Taliban chief Hakimullah Mehsud in a November 1 strike in the North Waziristan tribal area. Pakistan was outraged by the attack because it came a day before officials planned to invite Mehsud to hold peace talks.

Another police officer, Zia Khan, said three students and two teachers, all Afghans, were killed in the attack. Hangu police chief Iftikhar Ahmad said two of the dead, Mufti Hameedullah and Mufti Ahmad Jan, were members of the Afghan Haqqani network, one of the most feared militant groups battling US troops in Afghanistan.

The covert CIA drone programme in Pakistan has been a constant source of tension between Islamabad and Washington. Pakistan regularly condemns the strikes in public as a violation of the country's sovereignty, but the government is known to have supported at least some of the attacks in the past.

AP