Al Qaeda’s second-highest leader, accused of being one of the masterminds of the deadly 1998 attacks on American embassies in Africa, was killed in Iran three months ago, intelligence officials have confirmed.

Abdullah Ahmed Abdullah, who went by the nom de guerre Abu Muhammad al-Masri, was gunned down on the streets of Tehran by two assassins on a motorcycle on Aug. 7, the anniversary of the embassy attacks. He was killed along with his daughter, Miriam, the widow of Osama bin Laden’s son Hamza bin Laden.

The attack was carried out by Israeli operatives at the behest of the United States, according to four of the officials. It is unclear what role if any was played by the United States, which had been tracking the movements of Mr. al-Masri and other Qaeda operatives in Iran for years.