Pakistan officials say U.S. drone strike kills top militant commander Maulvi Nazir, 12 others

Updated at 4:39 a.m. Eastern

PESHAWAR, Pakistan Pakistani and Afghan officials say two U.S. drone strikes in the tribal regions bordering Afghanistan have killed 13 people, including a senior militant commander who had a truce with Pakistan's military.

Government and intelligence officials told CBS News that two missile strikes occurred early Thursday in the South and North Waziristan tribal areas.

They said the commander, Maulvi Nazir, was reportedly among nine people killed in the first strike in the village of Angoor Adda in South Waziristan. A senior government official in Peshawar, the largest city near the tribal areas, confirmed Nazir's death to CBS News' Farhan Bokhari.

The officials spoke on condition of anonymity because they were not authorized to brief the media.

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Residents in both Angoor Adda and Wana, the biggest town in South Waziristan, said they heard announcements on mosque loudspeakers announcing Nazir's death.

Bokhari said Nazir's death brought warnings that tension between the U.S. government and Pakistan, a difficult but vital ally in the war on Islamic extremism, could worsen.

The powerful militant commander was seen as an ally of Pakistan's security forces. Since 2011, he was reportedly behind a number of attacks targeting Western forces in Afghanistan, while simultaneously waging war against Taliban militants fighting Pakistan's army in the border region.

"Maulvi Nazir was seen as an asset by some Pakistani security circles," a senior Western diplomat in Islamabad told CBS News, suggesting his death would, "strain Pakistan's relations with the United States."

Reports of individual deaths are difficult to verify independently, and the U.S. rarely comments on its secretive drone program.

An Afghan intelligence official, and a Pakistani Taliban sub-commander, who told CBS News' Sami Yousafzai he served under Nazir, also acknowledged his death. The sub-commander lauded Nazir as "a committed jihad commander and tribal elder" and said his demise was a, "big blow for the Wazir tribe and jihad in Afghanistan."

The sub-commander said Nazir had not been "fighting against the Pakistani army under current circumstances," and his priority was "wining jihad against the U.S. and NATO forces in Afghanistan."

The Afghan intelligence source told Yousafzai that Nazir had been organizing Afghan and Pakistani militants -- in an "understanding" with Pakistan's ISI intelligence agency -- and sending them across the border to fight in Afghanistan.

The ISI is regularly accused of maintaining links to several Islamic militant groups in Pakistan, though the agency insists all historic links with the groups have been severed.

The U.S. drone strikes have helped debilitate al Qaeda in the Pakistan-Afghanistan border region, and Western officials say they help keep pressure on militants in the area.

Pakistani leaders regularly denounce the covert strikes, which have infuriated the nation's public and greatly exacerbated anti-U.S. sentiment in the country.

A convoy of thousands of Pakistani protesters, joined by a small contingent of American and British anti-war activists calling for an end to the U.S. drone strikes, was blocked by the Pakistani military in October from entering South Waziristan.

Led by opposition politician and former cricket star Imran Khan, the event dubbed a "peace march" drew about 30 activists from U.S. anti-war group CODEPINK, and a handful more from the British group Reprieve.

The protest convoy was blocked by Pakistani police at least four times during the day-long journey from the northern city of Dera Ismail Khan to the border of South Waziristan -- where many of the drone strikes have taken place.

According to Reprieve, 176 Pakistani children have been killed in drone strikes since the program began eight years ago.

Organizers of the diverted "peace march" argue, however, that the strikes are terrorizing the 800,000-odd innocent residents of North and South Waziristan who are not linked to Islamic extremist militants. They also say the strikes are illegal under international law and are serving as valuable propaganda tools for the very militant groups they target - creating new enemies faster than the old ones can be killed, according to CODEPINK co-founder Medea Benjamin.