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PESHAWAR, Pakistan (AP) -- Pakistan has evidence that al-Qaida's second-in-command was in a house destroyed by a U.S. drone strike in the country's northwest tribal region, but it is unclear whether he was killed, intelligence officials said Tuesday.

U.S. officials have said they were targeting Abu Yahya al-Libi in Monday's strike in Khassu Khel village in the North Waziristan tribal area and were "optimistic" he was among those killed. They spoke on condition of anonymity because of the classified nature of the drone program.

If al-Libi is confirmed killed, he would be the latest in the dozen-plus senior commanders removed in the clandestine U.S. war against al-Qaida since Navy SEALs killed Osama bin Laden last year.

Militants and residents in the area told Pakistani agents that al-Libi was in the house when it was hit, Pakistani intelligence officials said. They said the mud and brick house was completely destroyed in the attack.

A vehicle used by al-Libi was destroyed during the strike, said one of the officials. Agents intercepted a militant phone call indicating an Arab was killed in the attack, but it is unclear if they were talking about al-Libi, who was born in Libya, said the official.

A local Taliban chief said al-Libi's guard and driver were killed in the strike, but the al-Qaida commander was not there. Al-Libi did survive a previous strike, said the Taliban chief.

The intelligence officials spoke on condition of anonymity because they were not authorized to talk to the media. The Taliban spoke on condition of anonymity for fear of being targeted by the Pakistani army.

The White House maintains a list of terrorist targets to be killed or captured, compiled by the military and the CIA and ultimately approved by the president.

The U.S. has stepped up drone strikes in Pakistan recently, carrying out seven in less than two weeks. The flurry follows a relative lull driven by tensions between Washington and Islamabad over American airstrikes last year that killed 24 Pakistani soldiers.

Pakistan seized the opportunity to renegotiate its relationship with the U.S. and demanded Washington stop drone strikes in the country - a demand the U.S. has ignored. The attacks are unpopular in Pakistan because many people believe they mostly kill civilians, an allegation disputed by the U.S.

Pakistan called Deputy U.S. Ambassador Richard Hoagland to the Foreign Ministry on Tuesday to protest the drone strikes.

"He was informed that the drone strikes were unlawful, against international law and a violation of Pakistan's sovereignty," said a statement sent by the Foreign Ministry to reporters.

Members of the Pakistani government and military have supported the strikes in the past, but that cooperation has come under strain as the relationship between the two countries has deteriorated.

The State Department's Rewards for Justice program had set a $1 million reward for information leading to al-Libi, who had filmed numerous propaganda videos urging attacks on U.S. targets after he escaped a prison at Bagram Air Base in Afghanistan in 2005.

Al-Libi took the second-in-command spot when Egyptian-born Ayman al-Zawahri took charge of al-Qaida after bin Laden's death. As al-Qaida's de facto general manager, al-Libi is responsible for running the group's day-to-day operations in Pakistan's tribal areas and manages outreach to al-Qaida's regional affiliates.

"This is one of the more prominent names" among the targets of drone strikes in Pakistan, added former CIA officer Paul Pillar.

He said al-Libi's death would help bolster the CIA's push to continue the drone program despite the continued political resistance from Pakistan and collateral damage.

Al-Libi's death would be "another reason not to accept Pakistan's demand for an end to drone wars," added Brookings Institute's Bruce Riedel, a former CIA officer and adviser to the White House on Afghanistan and Pakistan policy.

Iran claimed Sunday that it had reverse-engineered an American spy drone captured by its armed forces last year and has begun building a copy.

Gen. Amir Ali Hajizadeh, chief of the aerospace division of the powerful Revolutionary Guards, related what he said were details of the aircraft's operational history to prove his claim that Tehran's military experts had extracted data from the U.S. RQ-170 Sentinel captured in December in eastern Iran, state television reported.

Among the drone's past missions, he said, was surveillance of the compound in northwest Pakistan in which Osama Bin Laden lived and was killed.

Tehran has flaunted the capture of the Sentinel, a top-secret surveillance drone with stealth technology, as a victory for Iran and a defeat for the United States in a complicated intelligence and technological battle.

U.S. officials have acknowledged losing the drone. They have said Iran will find it hard to exploit any data and technology aboard it because of measures taken to limit the intelligence value of drones operating over hostile territory.

Hajizadeh told state television that the captured surveillance drone is a "national asset" for Iran and that he could not reveal full technical details. But he did provide some samples of the data that he claimed Iranian experts had recovered.

"There is almost no part hidden to us in this aircraft. We recovered part of the data that had been erased. There were many codes and characters. But we deciphered them by the grace of God," Hajizadeh said.

He said all operations carried out by the drone had been recorded in the memory of the aircraft, including maintenance and testing.

Hajizadeh claimed that the drone flew over Osama Bin Laden's compound in Pakistan two weeks before the al-Qaida leader was killed there in May 2011 by U.S. Navy SEALs. He did not say how the Iranian experts knew this.

Before that, he said, "this drone was in California on Oct. 16, 2010, for some technical work and was taken to Kandahar in Afghanistan on Nov. 18, 2010. It conducted flights there but apparently faced problems and (U.S. experts) were unable to fix it," he said.

Hajizadeh said the drone was taken to Los Angeles in December 2010 where sensors of the aircraft underwent testing at an aerospace factory.

"If we had not achieved access to software and hardware of this aircraft, we would be unable to get these details. Our experts are fully dominant over sections and programs of this plane," he said. "It's not that we can bring down a drone but cannot recover the data."

There are concerns in the U.S. that Iran or other states may be able to reverse-engineer the chemical composition of the drone's radar-deflecting paint or the aircraft's sophisticated optics technology that allows operators to positively identify terror suspects from tens of thousands of feet in the air.

There are also worries that adversaries may be able to hack into the drone's database, as Iran claimed to have done. Some surveillance technologies allow video to stream through to operators on the ground but do not store much collected data. If they do, it is encrypted.

Media reports claimed this week that Russia and China have asked Tehran to provide them with information on the drone but Iran's Defense Ministry denied this.

(Reuters) - The death of a senior al Qaeda leader in a U.S. drone strike in Pakistan's tribal badlands, the first strike in almost two months, signaled that the U.S.-Pakistan intelligence partnership is still in operation despite political tensions.

The Jan 10 strike -- and its follow-up two days later -- were joint operations, a Pakistani security source based in the tribal areas told Reuters.

They made use of Pakistani "spotters" on the ground and demonstrated a level of coordination that both sides have sought to downplay since tensions erupted in January 2011 with the killing of two Pakistanis by a CIA contractor in Lahore.

"Our working relationship is a bit different from our political relationship," the source told Reuters, requesting anonymity. "It's more productive."

U.S. and Pakistani sources told Reuters that the target of the Jan 10 attack was Aslam Awan, a Pakistani national from Abbottabad, the town where Osama bin Laden was killed last May by a U.S. commando team.

They said he was targeted in a strike by a U.S.-operated drone directed at what news reports said was a compound near the town of Miranshah in the border province of North Waziristan.

That strike broke an undeclared eight-week hiatus in attacks by the armed, unmanned drones that patrol the tribal areas and are a key weapon in U.S. President Barack Obama's counter-terrorism strategy.

The sources described Awan, also known by the nom-de-guerre Abdullah Khorasani, as a significant figure in the remaining core leadership of al Qaeda, which U.S. officials say has been sharply reduced by the drone campaign. Most of the drone attacks are conducted as part of a clandestine CIA operation.

The Pakistani source, who helped target Awan, could not confirm that he was killed, but the U.S. official said he was. European officials said Awan had spent time in London and had ties to British extremists before returning to Pakistan.

The source, who says he runs a network of spotters primarily in North and South Waziristan, described for the first time how U.S.-Pakistani cooperation on strikes works, with his Pakistani agents keeping close tabs on suspected militants and building a pattern of their movements and associations.

"We run a network of human intelligence sources," he said. "Separately, we monitor their cell and satellite phones.

"Thirdly, we run joint monitoring operations with our U.S. and UK friends," he added, noting that cooperation with British intelligence was also extensive.

Pakistani and U.S. intelligence officers, using their own sources, hash out a joint "priority of targets lists" in regular face-to-face meetings, he said.

"Al Qaeda is our top priority," he said.

He declined to say where the meetings take place.

Once a target is identified and "marked," his network coordinates with drone operators on the U.S. side. He said the United States bases drones outside Kabul, likely at Bagram airfield about 25 miles north of the capital.

From spotting to firing a missile "hardly takes about two to three hours," he said.

DRONE STRIKES A SORE POINT WITH PAKISTAN

It was impossible to verify the source's claims and American experts, who decline to discuss the drone program, say the Pakistanis' cooperation has been less helpful in the past.

U.S. officials have complained that when information on drone strikes was shared with the Pakistanis beforehand, the targets were often tipped off, allowing them to escape.

Drone strikes have been a sore point with the public and Pakistani politicians, who describe them as violations of sovereignty that produce unacceptable civilian casualties.

The last strike before January had been on Nov 16, 10 days before 24 Pakistani soldiers were killed in what NATO says was an inadvertent cross-border attack on a Pakistani border post.

That incident sent U.S.-Pakistan relations into the deepest crisis since Islamabad joined the U.S.-led war on militancy following the Sept 11, 2001 attacks. On Thursday, Pakistani foreign minister Hina Rabbani Khar said ties were "on hold" while Pakistan completes a review of the alliance.

The United States sees Pakistan as critical to its efforts to wind down the war in Afghanistan, where U.S.-led NATO forces are battling a Taliban insurgency.

Some U.S. and Pakistani officials say that both sides are trying to improve ties. As part of this process, a U.S. official said, it is possible that some permanent changes could be made in the drone program which could slow the pace of attacks.

The security source said very few innocent people had been killed in the strikes. When a militant takes shelter in a house or compound which is then bombed, "the ones who are harboring him, they are equally responsible," he said.

"When they stay at a host house, they (the hosts) obviously have sympathies for these guys."

He denied that Pakistan helped target civilians.

"If ... others say innocents have been targeted, it's not true," he said. "We never target civilians or innocents."

The New America Foundation policy institute says that of 283 reported strikes from 2004 to Nov 16, 2011, between 1,717 and 2,680 people were killed. Between 293 and 471 were thought to be civilians -- approximately 17 percent of those killed.

The Brookings Institution, however, says civilian deaths are high, reporting in 2009 that "for every militant killed, 10 or more civilians also died." Pakistan's interior minister, Rehman Malik, also said in April 2011 that "the majority of victims are innocent civilians."

Still, despite its public stance, Pakistan has quietly supported the drone program since Obama ramped up air strikes when he took office in 2009 and even asked for more flights.

According to a U.S. State Department cable published by anti-secrecy organization WikiLeaks, Pakistan's chief of army staff General Ashfaq Kayani in February 2008 asked Admiral William J. Fallon, then-commander of U.S. Central Command, for increased surveillance and round-the-clock drone coverage over North and South Waziristan.

The security source said Pakistan's powerful spy agency, the Directorate of Inter-Services Intelligence, also was supportive of the strikes, albeit privately.

President Barack Obama said Monday that the United States has asked Iran to return a U.S. drone aircraft that Iran claims it recently brought down in Iranian territory.

"We've asked for it back. We'll see how the Iranians respond," Obama said in a news conference.

The president's comments come one day after it was reported that an Iranian official said the country would not return the drone.

"No nation welcomes other countries' spy drones in its territory, and no one sends back the spying equipment and its information back to the country of origin," said Gen. Hossein Salami, deputy commander of the Armed Forces, according to the semi-official Fars news agency.

"It makes no difference where this drone originated and which group or country sent it to invade our air space," Salami said. "This was an act of invasion and belligerence."