Al Qaeda has named Ayman al-Zawahiri as its new chief to succeed the slain Osama bin Laden.

In a statement posted on an Islamist website, the jihadist network said under Zawahiri's leadership, Al Qaeda would pursue its jihad against the United States and Israel.

"We seek with the aid of God to call for the religion of truth and incite our nation to fight... by carrying out jihad against the apostate invaders... with their head being crusader America and its servant Israel and whoever supports them," the statement said.

The fight would continue "until all invading armies leave the land of Islam".

"We support the uprisings of our oppressed Muslim people against the corrupt and tyrant leaders who have made our nation suffer in Egypt, Tunisia, Libya, Yemen, Syria and Morocco," said the statement, referring to a wave of revolts that have rocked the Middle East and North Africa since December.

The protests have succeeded in toppling autocrats in Egypt and Tunisia, while others, such as Libya's Moamar Gaddafi and Syria's Bashar al Assad, are still battling uprisings in their countries.

Al Qaeda urged those involved in the uprisings to continue their "struggle until the fall of all corrupt regimes that the West has forced onto our countries".

Zawahiri, the group's long-time number two, succeeds bin Laden, who was killed by US commandos in a May 2 raid in Pakistan.

Like his slain Saudi-born co-conspirator, the 60-year-old Egyptian surgeon Zawahiri has been hiding ever since the US declared its war on terror after the September 11, 2001 attacks.

Zawahiri, now the United States's most wanted man, was jailed for three years in Egypt for militancy and was implicated in the assassination of Egyptian president Anwar Sadat in 1981 and a 1997 massacre of tourists in Luxor.

Facing a death sentence, he left Egypt in the mid-1980s initially for Saudi Arabia, but soon headed for Pakistan's north-western city of Peshawar, where the resistance to the Soviet occupation of Afghanistan was based, and then to Afghanistan, where he joined forces with bin Laden.

His current whereabouts is unknown.

- AFP