A U.S. drone aircraft fired a missile into a militant compound in the Pakistani region of North Waziristan on the Afghan border, killing five militants, security officials said on Saturday.
The United States has stepped up drone strikes on sanctuaries for al Qaeda and Taliban militants on the Pakistani side of the Afghan border since a bomb attack on U.S. intelligence agents across the border in Afghanistan's Khost province on Dec. 30.
The latest attack, the 12th this month according to a Reuters tally, happened 20 km (12 miles) west of Miranshah, the main town in North Waziristan, late on Friday.
"The missile struck a compound used by militants and we have reports of five dead. Two of them were foreigners," said a security official in the region, who declined to be identified.
The nationality and identity of the foreigners was not known, he said.
The United States sees the elimination of militant enclaves in northwest Pakistan, from where the Taliban orchestrate their insurgency in Afghanistan and al Qaeda plots violence further afield, as vital for bringing stability to Afghanistan.
But the drone strikes are a source of friction with Pakistan even though some leaders of its indigenous Taliban who are battling the state have been killed.
Pakistan says the attacks violate its sovereignty and complicates its efforts against militancy by inflaming public anger.
Pakistan wants the United States to supply it with armed drones so it can do the job itself but the United States has only offered surveillance drones.
The latest strike came after an international meeting on Afghanistan in London where the Afghan government invited the Taliban to a peace council.
Pakistan could play an important role in using its links with the Afghan Taliban to bring them into talks.
The United States carried out 51 drone strikes in Pakistan last year compared with 32 in 2008, according to a Reuters tally.
The rate of attacks rose sharply early this month after the Dec. 30 attack in eastern Afghanistan when a a Jordanian suicide bomber killed seven CIA employees, the deadliest strike on the agency in decades.