In an audio recording released posthumously, Osama bin Laden has called for his followers to help efforts to bring down more of what he calls "tyrants" in the Muslim world.
Bin Laden was the leader of al Qaeda until he was killed in raid by US special forces in the Pakistan city of Abbottabad.
Al Qaeda had said bin Laden, who masterminded the September 11 attacks on the United States in 2001, recorded a message a week before his death, Reuters reports.
The audio was included in an internet video lasting at least 12 minutes and posted on Islamist websites. Bin Laden praised revolutions sweeping the Arab world which began in Tunisia.
Tunisia's president Zine al-Abidine Ben Ali was overthrown in January this year, followed by Egyptian leader Hosni Mubarak after mass protests centred on Cairo's Tahrir Square.
Bin Laden called on al Qaeda supporters to set up an operations room to follow up events and work in parallel to save the people struggling to bring down their tyrants.
