A Pakistani security official on Thursday said at least three top Al Qaeda operatives were believed killed in a U.S. missile strike last week, including an explosives expert on the U.S. most-wanted list and a close relative of the terror network's No. 2 leader Ayman al-Zawahri.

The security official, speaking on condition of anonymity because he's not authorized to speak to media, said Egyptian Midhat Mursi was among the three top Al Qaeda figures who were present in Damadola village at the time of the attack and whose bodies were believed to have been taken away by sympathizers of the group.

No U.S. officials could immediately confirm the Pakistani official's statements.

The U.S. Justice Department names Midhat Mursi al-Sayid Umar, also known as Abu Khabab al-Masri, as an explosives expert and poisons trainer who operated a terrorist training camp at Derunta, near the eastern city of Jalalabad in Afghanistan.

It says his exact whereabouts are unknown but adds that he may be residing in Pakistan, and offers $5 million for information leading to his arrest.

The official named two other foreigners as suspected killed in the missile strike: Abu Ubaida, whom he said was the main operations chief for Al Qaeda in Afghanistan's eastern Kunar province, which lies opposite Pakistan's Bajur tribal region where Damadola is located; and Abdul Rehman al-Misri, an Egyptian and close relative of al-Zawahri, possibly his son-in-law.

He stressed that their bodies have not been found.

"We do not have any evidence to prove that they have been killed, but we have indications that they were there and were among those bodies that were taken away," said the official, declining to elaborate.

A second Pakistani security official confirmed that security agencies were investigating the three men as possible victims of the air strike Friday near the Afghan border. Officials say the attack also killed 18 local people.

The New York Times and ABC reported Thursday that al-Zawahri's son-in-law was also believed killed in the strike, but provided a different identity.

Click here to read the New York Times article on the strike.

The Associated Press contributed to this story.