Al-Qaeda chief Ayman al-Zawahiri was killed in a precision drone strike in Afghanistan’s Kabul, US president Joe Biden has confirmed

Zawahiri, 71, lacked the potent charisma that helped bin Laden rally jihadists around the world, but willingly channelled his analytical skills into the Al-Qaeda cause.

He was believed to be the main strategist -- the real mastermind who steered operations, including the September 11 attacks, as well as bin Laden's personal doctor.

Al-Qaeda is believed to have been degraded in the years since the US invasion of Afghanistan, and the White House official said Zawahiri was "one of the last remaining figures who carried this kind of significance."

The organization, agreed Soufan Centre researcher Colin Clarke, is "at a crossroads."

"Despite Zawahiri's leadership, which minimized AQ's losses while rebuilding, the group still faces serious challenges going forward. For one, there's the question of who will lead al Qaeda after Zawahiri's gone," he said.

Zawahiri's father was a renowned physician and his grandfather a prayer leader at Cairo's Al-Azhar institute, the highest authority for Sunni Muslims.

He became involved with Egypt's radical Muslim community at a young age and published several books which came for many to symbolize the radical Islamist movement.

He left Egypt in the mid-1980s, heading for Pakistan's north-western city of Peshawar where the resistance to the Soviet occupation of Afghanistan was based.

It was at that time, when thousands of Islamist fighters flooded into Afghanistan during the 1980s, that Zawahiri and bin Laden met, and in 1998 he became one of five signatories to bin Laden's "fatwa" calling for attacks against Americans.

Jihadist monitor SITE said some militants were questioning the veracity of the report he had been killed, while others believed Zawahiri had achieved his desire of "martyrdom."

As for Al-Qaeda's future without him, SITE said jihadists were bullish, with one writing: "If Sheikh Ayman al-Zawahiri is dead, there are a thousand Aymans."