In a special issue of Al-Qaeda English-language magazine Resurgence, editor Hassaan Yusuf wrote that Azzam, whose real name was Adam Gadahn, was killed in a strike thought to have taken place in January on an Al-Qaeda compound in Pakistan.
Yusuf also said Ahmed Faruq, an American described as a leader of Al-Qaeda in the Indian Subcontinent, and American and Italian hostages Warren Weinstein and Giovanni Lo Porto, were killed in another strike "a few weeks" prior.
Gadahn was a teenage death metal music fan who grew up on a California goat farm before he was drawn into radical Islam.
He was one of the most high-profile figures in the global jihadist movement and a regular online presence, taunting his homeland and inciting attacks.