Islamabad  - A suspected US pilotless aircraft on Saturday targeted a militant hideout in Pakistan's restive tribal region along the border with Afghanistan, killing four people and injuring six, a Pakistani intelligence official said.

Two hellfire missiles demolished the house of local Taliban leader Khaliq Noor in Ali Khel village outside Mir Ali, the main town in the tribal district of North Waziristan, a known sanctuary of Taliban and al-Qaeda fighters.

"According to our information, at least two of the four killed are foreigners," said the official, who spoke on the condition of anonymity because he was not authorized to talk to the media.

Pakistani officials often use the term foreigners to describe al-Qaeda-linked fighters of Arab or Central Asian origin

US forces in Afghanistan have conducted about two dozen airstrikes in Pakistan's tribal region in the past two months and at least one outside it - in the Bannu district of North-West Frontier Province.

The government in Islamabad said the actions violate its sovereignty and fuel public anger, complicating its efforts to fight terrorism.

Saturday's airstrike came two days after the Foreign Affairs Ministry summoned US Ambassador Anne Patterson to lodge a formal protest over the Bannu attack. (dpa)