A key associate of al-Qaida No. 2 Ayman al-Zawahri was tracked down with US help and killed by Pakistani security forces in a rocket attack near the Afghan border, officials said Saturday. Hamza Rabia, believed to have become al-Qaida's operational commander after the arrest of Abu Farraj al-Libbi in northwestern Pakistan in May, ranks somewhere between third and fifth in the terror network's hierarchy, officials said. He was among five people who died in an explosion Thursday in the North Waziristan tribal area. Information Minister Sheikh Rashid Ahmed said Rabia's remains were identified via a DNA test. While Ahmed backed the official line that the blast was set off as the victims were making explosives inside a suspected al-Qaida hideout, a senior intelligence official - speaking on condition of anonymity because he is not authorized to speak to media - said a missile attack triggered a huge explosion in a stockpile of bomb-making materials, grenades and other munitions. Another intelligence official said US help was involved in tracking Rabia down and "eliminating the threat" that he embodied. On Saturday, Pakistan's Dawn newspaper, citing unidentified sources, reported that the attack on a mud-walled home near Miran Shah may have been launched from two pilotless planes. Miran Shah is a strategic tribal region where remnants of al-Qaida are believed to have been hiding and where Pakistani forces have launched several operations against them. Intelligence officials said Rabia - who is Syrian - was the target of the attack due to his alleged involvement in dozens of terror attacks and murders of government officials in Pakistan's lawless tribal regions, and that he had been brought to the area by al-Zawahri, who is believed to have been on the run along the Pakistan-Afghan border. However, officials said they have no clue on the whereabouts of al-Zawahri or Osama bin Laden. Another official, who also didn't want to be named due to the sensitive nature of his job, said Rabi became operational commander of the terror network after the arrests of al-Libbi, known to be al-Qaida's No. 3 leader. Al-Libbi - who twice tried to assassinate Pakistan's President Gen. Pervez Musharraf for making the Islamic nation a key ally of the United States in its war on terror - was later turned over to Washington for further investigation. Pakistan's Information Minister Sheikh Rashid Ahmed described Rabia as al-Qaida operational commander in Pakistan's tribal regions. "He was al-Qaida's No. 5 and this is what we know," he told The Associated Press. Earlier a top government administrator, Syed Zaheerul Islam, had said that Rabia died in an explosion while making bombs at a home near Miran Shah. Islam said the blast also killed four other people, including two area residents, and left two others injured, who have not been identified. Associates from outside Pakistan retrieved the bodies of Rabia and two other foreigners and buried them in an unknown location, the Dawn newspaper report said. Military officials have said hundreds of Arab, Afghan and Central Asian militants are in North and South Waziristan. Pakistan - a key ally of the United States in the war against terrorism - has deployed thousands of troops in the area, fighting intense battles with militants and killing and capturing several of them.