President Bush's national security advisor says the U.S. government is looking into reports that one of al-Qaida's top leaders was killed Thursday in Pakistan, but cannot confirm his death.

Stephen Hadley told Fox News Sunday that at his point, Washington is not in a position publicly to confirm that Egyptian-born Abu Hamza Rabia is dead. But he said if he is, that is good news for the war on terror.

Mr. Hadley described Mr. Rabia as a bad guy who had become the head of operations for al-Qaida after the May capture in Pakistan of the terror network's previous operations chief, Abu Faraj al-Libbi.

Pakistani officials said Saturday that Abu Hamza Rabia, described as the number three in the al-Qaida hierarchy, was killed with four others by an explosion in Pakistan's northwestern tribal of North Waziristan.

He has been linked to several plots to attack the United States, as well as to attempts to assassinate Pakistani President Pervez Musharraf.

Some information for this report provided by AP and AFP.