Al-Qaeda has released a posthumous message from Osama bin Laden praising the revolutions in Egypt and Tunisia and urging Muslims to take advantage of a "rare historic opportunity" to rise up, according to a US monitoring service.

The 12-minute, 37-second audio message posted on jihadist forums by al-Qaeda's media arm As-Sahab addresses Muslims on the revolutions sweeping the Middle East and North Africa, said SITE Intelligence.

Speaking from beyond the grave, bin Laden recommended setting up a council to offer revolutionary advice and decide the best timing to spread revolt across the Muslim world.

"A delay may cause the opportunity to be lost, and carrying it out before the right time will increase the number of casualties," bin Laden says in the audio message, according to SITE's translation.

"I think that the winds of change will blow over the entire Muslim world, with permission from Allah."

He accused rulers of building themselves into idols and manipulating the media to stay in power.