CAIRO — Al-Qaida’s longtime No. 2 leader, a doctor from a prominent Egyptian family who worked with Osama bin Laden for decades, has succeeded the slain terrorist as head of the global network, the group said Thursday.

Ayman al-Zawahri, who turns 60 on Sunday, has long brought ideological fire, tactics and organizational skills to al-Qaida. The surgeon by training was first behind the use of the suicide bombings and independent terror cells that have become the network’s trademarks.

He is believed to be living somewhere near the Pakistan-Afghanistan border and has appeared in dozens of videos and audiotapes in recent years, increasingly becoming the face of al-Qaida as bin Laden kept a lower profile.

Al-Zawahri had been considered the most likely successor because of his longtime collaboration with bin Laden, and analysts had said that few were likely to challenge the al-Qaida deputy leader for the top spot.

Al-Zawahri and bin Laden first crossed paths in the late 1980s in the caves of Afghanistan.

He heaped praise on bin Laden, who was killed in a May 2 raid by U.S. Navy SEALs in Pakistan, and criticized the U.S. for burying him at sea.

“He went to his God as a martyr, the man who terrified America while alive and terrifies it in death, so much so that they trembled at the idea of his having tomb,” he said.