It said in a brief news flash the Egyptian militant Saif al-Adel was named interim leader, while Mustafa al-Yemeni, whose nationality it did not give, would direct operations.
U.S. special forces shot dead Al Qaeda leader bin Laden in his hideout outside the capital of Pakistan earlier this month.
U.S. prosecutors say Adel is one of al Qaeda’s leading military commanders and helped plan the bomb attacks against the American embassies in Nairobi and Dar es Salaam in 1998.
They also say he set up al Qaeda training camps in Sudan and Afghanistan in the 1990s.
An al Qaeda expert had said on Tuesday that Adel would likely not act as head of the organization.
“This role that he has assumed is not as overall leader, but he is in charge in operational and military terms,” said Noman Benotman, a former bin Laden associate who is now an analyst with Britain’s Quilliam Foundation think tank.
Adel was believed to have fled to Iran after the U.S. invasion of Afghanistan following the September 11, 2001 attacks on the United States, and was subsequently held under a form of house arrest there, according to some media reports.
Arab media reports said Iranian authorities released him from custody about a year ago, and he then moved back to the Afghanistan-Pakistan border region. Some analysts say Adel may have returned to Iran or Afghanistan in recent weeks. Reuters