Pakistan had no confirmation Friday that al-Qaida's chief of operations in the country had been killed in a recent drone strike in the northwestern tribal region, as reported by American officials.

Abu Hafs al-Shahri, a Saudi who had been serving as the senior figure in newtwork's central command, was the target of a drone strike within the last few days, two U.S. officials said Thursday.

We have no knowledge of that, a Pakistani military spokesman, Maj. Gen. Athar Abbas, told Reuters.

Intelligence officials operating in the tribal regions near the Afghan border also had no information on al-Shahri.

We have neither heard of this man operating in this region, nor can we confirm his death, said one.

While U.S. officials declined to provide precise details, the only drone strike this month occurred on Sunday when a U.S. drone targeted a militant compound near the town of Mir Ali in North Waziristan that killed at least three suspected militants.

If his death is confirmed, al-Shahri would be the sixth senior al-Qaida figure killed by either U.S. or Pakistani forces in Pakistan since May, including Osama bin Laden.

Two Pakistani intelligence officials said two of the dead in that strike were Pakistani militants, but had no information about the third target. Another intelligence official said he was of Arab origin, but had no further details.

Taliban militants were not immediately available for comments.

Militants usually quickly bury their dead after drone strikes, making if difficult to verify that U.S. or Pakistani operations had succeeded.

The unruly, mountainous northwest region is hard to access as well.

As Pakistan operations chief, one of the U.S. officials said, al-Shahri's responsibilities included coordinating the activities of al- Qaida's depleted central leadership with Pakistan's principal network of Taliban militants, known as the TTP.

Another senior al-Qaida leader, Younis al Mauritani, was recently captured in Pakistan's tribal areas in a joint operation staged by U.S. and Pakistani security forces.

That operation was hailed by Washington and Islamabad as an example of strong counterterrorism cooperation.

Those comments suggested the United States and Pakistan had put behind them bitterness caused by the unilateral raid that killed bin Laden.

But there are signs of new strains in the alliance.

The U.S. warning on militants based in Pakistan, blamed by Washington for this week's attack on the U.S. Embassy in Kabul, works against counterterrorism cooperation between the two allies, the Pakistan Foreign Ministry said Thursday.

It was referring to comments by U.S. Defense Secretary Leon Panetta that Washington would do whatever it takes to defend American forces in Afghanistan from Pakistan-based militants.

(Reporting by Qasim Nauman in Islamabad, Saud Mehsud in Dera, Ismail Khan and Haji Mujtaba in Miranshah; Writing by Augustine Anthony; Editing by Michael Georgy and Ed Lane)