"The general command of Al-Qaeda announces, after consultations, the appointment of Sheikh Ayman al-Zawahiri as head of the group," the jihadist network said in statement posted on an Islamist website.[break]
Zawahiri, the group´s long-time number two, succeeds bin Laden who was killed by US commandos in a May 2 raid in Pakistan.
The statement said that under Zawahiri´s leadership Al-Qaeda would pursue its ´jihad´ (holy war) 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," said the statement.
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 Moamer Kadhafi 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."
Like his slain Saudi-born co-conspirator, the 60-year-old Egyptian surgeon Zawahiri has been hiding ever since the United States declared its war on terror after the September 11, 2001 attacks.
Zawahiri, now the United State´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 northwestern 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.