A suspected U.S. missile strike that killed up to 13 foreign militants in Pakistan's North Waziristan region this week had targeted second or third tier al Qaeda leaders, according to residents in the tribal area.

Initial reports said 10 people were killed in the attack on Monday on a house in Torkhali village near the town of Mir Ali.

An intelligence official, however, told Reuters on Thursday that based on information gleaned from tribal contacts there were seven Arabs and six Central Asians killed.

He said the attack was believed to have been carried out by a pilotless U.S. Predator aircraft flown across the nearby border with Afghanistan.

The missile appeared to have been fired by a drone, the intelligence official said.

The Pakistani authorities have not confirmed the attack, and the Pentagon has denied taking any action, but the Defense Department does not speak for the Central Intelligence Agency, which operates Predators that the tribesmen say carried out the attack late on Monday.

Villagers saw two drones flying over the area before the attack. They didn't see the missile being fired but one heard a plane's engine before the explosion.

Intelligence officials said the area is controlled by Islamist militants and too dangerous for security forces to go. After the attack, militants surrounded the area and barred anyone from going near the house.

Ahmed Aziz, a 70-year-old resident, told Reuters that the militants also stopped villagers from attending the funerals, which was a sign that those killed were all foreigners.

When local people die, they don't stop anyone from attending their funerals, Aziz said.

Tribesmen in the area said a deputy of Abu Laith al Libi, a senior al Qaeda leader, had been staying there and was among the dead, according to the intelligence official.

The latest information we have from the area is that a second-in-command to al Libi was among those killed, he said.

A leading Pakistani daily, The News, reported that the strike had targeted Libi and another senior figure, Obaidah al Masri, though neither was present at the time of the attack according to a senior Taliban commander quoted by the newspaper.

Libi and Masri were promoted up the al Qaeda ranks due to successful U.S. and Pakistani operations in the past to catch or kill the guerrilla network's second tier leaders.

U.S. forces in Afghanistan have launched similar attacks on al Qaeda targets on the Pakistani side of the border several times in recent years.

If it was a U.S. drone attack, the lack of confirmation is not unusual. Pakistan says it will not tolerate violations of its territorial sovereignty and reports of such attacks are embarrassing for the U.S.-Pakistani alliance.

(Writing by Simon-Cameron Moore; Editing by Sanjeev Miglani)

Pakistan Afghanistan Terrorism