Updated

Two important Al Qaeda operatives were among four foreign militants killed in a CIA missile strike in Pakistan's northwest, officials said Wednesday.

Some Pakistani intelligence officials said one of the men was in charge of the terror network's activities in Pakistan's tribal regions, semiautonomous areas that the U.S. fears have become a haven for Al Qaeda and Taliban fighters.

However, another Pakistani official said none of the four appeared to be members of Al Qaeda's top leadership and a U.S. official said he believed the militants were mid-level operatives.

The missile strike occurred Monday in the North Waziristan tribal region, destroying a seminary and houses associated with a veteran Taliban commander. The tribal belt is considered a possible hiding place for Usama bin Laden and Al Qaeda No. 2 Ayman al-Zawahri.

Several suspected missile strikes in recent days have indicated the U.S. is escalating direct efforts to root out militants along the lengthy, porous Afghan-Pakistan border.

U.S. officials say the elimination of insurgent hideouts in Pakistan is critical to stemming the growing Taliban insurgency in Afghanistan. Pakistan's fledgling government has struggled to contain militancy, despite using peace talks and force.

Three Pakistani intelligence officials identified four foreign militants killed in the Monday strike as Abu Qasim, Abu Musa, Abu Hamza and Abu Haris. The officials spoke on condition of anonymity because of their jobs' sensitivity.

Abu Haris led Al Qaeda efforts in the tribal areas, while Abu Hamza led activities in Peshawar, the main northwest city, according to the intelligence officials, who said they got the details from informants and agents in the field.

Abu Haris' nationality had yet to be confirmed, but Abu Hamza was from Saudi Arabia, the officials said. Abu Hamza was believed to be a bomb-making expert. Abu Qasim was Egyptian, while Abu Musa also was Saudi, but both appeared to be lower-ranking Al Qaeda members.

Mohammed Amir Rana of the Pakistan Institute for Peace Studies, which tracks militant groups in the region, said a militant using the name Abu Haris was believed to train Pakistani homicide bombers and coordinate Taliban and Al Qaeda activities in the tribal belt.

Another Pakistani intelligence official said there had been no chatter in security circles of a meeting of high-level commanders in North Waziristan before or after the attack.

Two U.S. officials said the strike was carried out by the CIA, but didn't have detailed information on the roles of Abu Haris and Abu Hamza. The American officials spoke on condition of anonymity because they were not authorized to discuss CIA operations.

One said he believed they were mid-level operatives who played an important role in the decentralized militant network.

An army spokesman, Maj. Murad Khan, said Wednesday the military had no information about the identity or nationality of the men killed in what he called "explosions" in North Waziristan.

Two of the Pakistani intelligence officials said Tuesday that the overall death toll from the strike rose to 20 after residents and militants pulled more bodies from the rubble.

Witnesses said two Predator drones were in the sky shortly before multiple explosions hit the seminary and houses in the village of Dande Darba Khel on Monday morning.

The targets were associated with Jalaluddin Haqqani, a veteran of the fight against Soviet troops in Afghanistan in the 1980s who American commanders now count as a dangerous foe. Haqqani is alleged to have close connections to Al Qaeda and to have helped funnel foreign fighters into Afghanistan.

Haqqani and his son, Siraj, have been linked to attacks this year including an attempt to kill Afghan President Hamid Karzai and a homicide attack on a hotel in Kabul. Haqqani network operatives also plague U.S. forces in Afghanistan's eastern Khost province with ambushes and roadside bombs.

"The American missile attacks were aimed at targeting Jalaluddin or Siraj, but we know that they were not there," said another senior Pakistani intelligence official.