Thousands of people went to the airport to welcome Rachid Ghannouchi, 69, as he arrived in Tunis from London.

He has said he will not run in the next presidential poll but his party will contest a parliamentary election.

Observers say his return is the most potent symbol yet of the change that has swept the country since then.

Mr Ghannouchi fled Tunisia after a crackdown President Ben Ali against his banned Ennahda movement.

He returned after the interim government's announced that media curbs would be lifted, banned political parties allowed to register and political prisoners given amnesty.

Up to 10,000 young men and veiled women packed the arrival hall and car park at the airport, and some climbed trees and electricity pylons to catch a glimpse of Mr Ghannouchi.

Alongside his supporters was a small group of secularists with banners reading: "No Islamism, no theocracy, no Sharia and no stupidity!"