Al Qaeda released a posthumous audio recording by Osama bin Laden in which the group's ex-leader praised revolutions sweeping the Arab world, and called for more "tyrants" to be toppled.
Islamists have often been conspicuous by their absence in the uprisings largely led by ordinary citizens angered by autocratic rule, corruption and economic mismanagement.
But bin Laden, who was killed in a US raid on May 2 in Pakistan, backed the uprisings which began in Tunisia and have spread across much of North Africa and the Middle East.
Al Qaeda had said bin Laden, who masterminded the Sept. 11, 2001, attacks on the United States, recorded a message a week before his death. The audio was included in an Internet video lasting more than 12 minutes and posted on Islamist websites.
In the audio, a voice which appears to be bin Laden's referred to the uprisings which began in the Maghreb region of North Africa.
"The sun of the revolution has risen from the Maghreb. The light of the revolution came from Tunisia. It has given the nation tranquility and made the faces of the people happy."
Tunisia's president Zine al-Abidine Ben Ali was overthrown in January, followed by Egyptian leader Hosni Mubarak after mass protests centred on Cairo's Tahrir Square.
Bin Laden backed efforts to topple more leaders in the Muslim world, calling on al Qaeda supporters to "set up an operations room that follows up events and works in parallel ... to save the people that are struggling to bring down their tyrants".
"Tunisia was the first but swiftly the knights of Egypt have taken a spark from the free people of Tunisia to Tahrir Square," said bin Laden, adding: "It has made the rulers worried."