Intelligence officials suspect a top militant leader may have been killed in an alleged U.S. missile strike because the Taliban are unusually angry about the attack.

Amid reports of the death toll rising to 24, informants and agents in the field said members of the Taliban seem particularly incensed by the latest strike.

The fury is a sign that a senior Taliban leader may have been killed, though that has yet to be confirmed, the officials said Sunday.

The insurgents were using harsh language against locals, calling them "saleable commodities" — a reference to people serving as government spies, according to the sources.

Two local residents said Taliban fighters had warned people not to discuss the strike with anyone including the media or try inspecting the rubble at the site. The residents asked not to be named for fear of Taliban retaliation.

The strike in Mohammadkhel appeared to be the deadliest of 11 reported cross-border operations by U.S.-led forces since Aug. 20. The area is a stronghold of Jalaluddin Haqqani, a veteran Taliban commander regarded by the U.S. as one of its most dangerous foes.

The U.S. rarely acknowledges such attacks; and 1st Lt. Nathan Perry, a spokesman for the U.S.-led coalition in Afghanistan, said he had "no information to give" about the reported missile strikes. He did not deny U.S. involvement.

Taliban spokesmen and representatives from the Pakistani government and military could not immediately be reached for comment Sunday.

Pakistan army spokesman Maj. Gen. Athar Abbas said initial reports indicated that 20 or more people were killed. He said there was "speculation" that many were foreign militants, but cautioned the army was still awaiting a detailed report.

The frontier region is believed to be a possible hiding place for Al Qaeda leader Usama bin Laden and his deputy Ayman al-Zawahri. Several Arab militants were said to be among the dead in Friday's strike in North Waziristan tribal region.

Two Pakistani intelligence officials said that over the weekend two people wounded in the attack died at a hospital in Miran Shah, the main town in North Waziristan. The officials sought anonymity because they were not authorized to speak to media.

Pakistan's military and civilian leaders have complained that such missile strikes violate the country's sovereignty, kill civilians and anger the local population, making it harder to crack down on militants.

Extremists based in the border region are blamed for rising attacks in Pakistan, including the Sept. 20 truck bombing of the Marriott Hotel in Islamabad that killed more than 50 people.

The prime minister's office announced Saturday that a special joint session of parliament would be held Wednesday so intelligence agencies could privately brief lawmakers about the militant threat facing the country.

Ahsan Iqbal, a top member of the lead opposition party, welcomed the joint session saying it could help clarify U.S. motives in launching operations in Pakistan.

"Before this, America did a very big war operation in Iraq," he told GEO television. "That time, too, America said that there was an intrusion in Iraq from Syria and Iran but we saw nowhere that America could have violated the borders of Syria or Iran."

The Pakistani military has been carrying out its own operations against insurgents in the northwest, most notably in Bajur, a tribal region Abbas called a "mega-sanctuary" for militants.

The U.S. has praised the military offensive in Bajur, but it has also led to a major humanitarian crisis. Hundreds of thousands of civilians have been displaced by the fighting.

Many are in refugee camps in Pakistan, but some 20,000 Pakistanis have sought crossed the border into eastern Afghanistan, according to the United Nations.

Also Sunday, an official said some 15,000 Afghans had left a tribal region in northwest Pakistan that the military is trying to wrest from insurgents. Tens of thousands more have yet to meet a government ultimatum to leave the region by Sunday.

The U.S. has ramped up cross-border strikes on alleged Al Qaeda and Taliban targets along Pakistan's side of the border with Afghanistan, straining the two nations' anti-terror alliance.

The U.S. says pockets of Pakistan's border region, especially in its semi-autonomous tribal areas, are bases for militants attacking American and NATO forces in Afghanistan. It has pushed nuclear-armed Pakistan to eliminate the safe havens.

Meanwhile, a three-day ultimatum from the government for Afghans living illegally in Bajur to leave was due to expire later Sunday. But of an estimated 80,000 Afghans, only about 15,000 had left, said Abdul Haseeb, a local government official.

He said the exodus appeared to be continuing, and that "the administration may be lenient and give them another couple of days."

"They are leaving with all their belongings and cattles and hopefully most of them will leave in another two days, but if they don't there would be a massive crackdown," Haseeb said.

Ghulam Jan, an Afghan who said he came to Pakistan years before as a child with his parents, was preparing to head across the border to Afghanistan's Kunar province with 13 members of his family, a cow and two calves.

"My parents are buried here. I consider this my homeland," he said. "Suddenly we are being uprooted to build our home anew in a hostile situation."