A U.S. drone strike early Friday killed six suspected militants and wounded three others in northwestern Pakistan near the Afghan border, Pakistani security officials said.

Two intelligence officials from the North Waziristan tribal district, a hotbed for Taliban and al-Qaeda fighters, said the drone attacked a house in the Ghulam Khan area.

In telephone interviews, the officials said a senior commander of the Haqqani network, Maulvi Sangeen Zadran, was believed to be among the dead. The officials spoke on condition of anonymity because they are not authorized to speak publicly.

There was no immediate confirmation of Zadran’s death from independent sources. Nor was there any word about the strike from the Haqqani network or other Taliban groups.

The Haqqani network, an Islamist insurgent group formed by the Haqqani family of southeastern Afghanistan, is allied with the radical Muslim Taliban movement and operates on both sides of the Afghan-Pakistani border. U.S. officials believe it is based in Pakistan’s Waziristan region.

The sprawling compound near the border town of Ghulam Khan was hit by a pair of missiles, the Associated Press reported. The identites and nationalities of the slain men were not immediately known, and agents were investigating, it said.

AP added:

U.S. officials consider the Haqqani network to be one of the most dangerous militant factions fighting American troops in neighboring Afghanistan.

North Waziristan is a tribal region home to a mix of Pakistani, Afghan and al-Qaeda-linked foreign militants.

The U.S. drone program causes extreme tension between Pakistan and the United States, though some Pakistani officials privately acknowledge the need for the strikes as its military rarely patrols the area. Washington says it needs to use the unmanned aircraft because Pakistan refuses to engage the fighters.

Thursday’s strike came less than a week after a U.S. drone killed three foreign militants in an abandoned seminary in the same region.

Pakistan strongly condemned previous strikes, calling them “unilateral” and a violation of country’s sovereignty and territorial integrity. On Friday, Pakistan’s Foreign Ministry again called for an end to the drone attacks, saying such “strikes are counter-productive, entail loss of innocent civilian lives and have human rights and humanitarian implications.”

“Such strikes also set dangerous precedents in the inter-state relations,” the ministry said in a statement.