A Tunisian court has sentenced two youths to prison for posting caricatures of the Prophet Mohammed on Facebook, officials said Thursday in a case highlighting religion's growing role in the post-revolutionary country.

"They were sentenced, one of them in absentia, to seven years in prison for transgressing morality, defamation and disrupting public order," ministry spokesman Chokri Nefti told AFP.

The sentences were handed down 28 March and defence lawyers have appealed. One of the two young men was jailed, but the other was not in court for the verdict. They are both from the town of Mahdia, around 200 kilometres (120 miles) south of Tunis.

The case started when two Mahdia residents, one of them a lawyer, complained in early March about having seen the images online, according to blogger Olfa Riahi.

The defendants had posted "cartoons depicting the Prophet in the nude ... and slandering high-profile Tunisian figures" on their Facebook page, Nefti said.

"This sentence is much too harsh," rights activist Bochra Bel Haj Hmida told AFP, adding she had petitioned the presidency over the matter.

"They are just two young graduates who thought they were free to say they are atheists and thought they were protected on Facebook," she added.

The activist warned the convictions were precedent setting.

"Before, no one cared about what happened on Facebook," she said.

The number of trials on charges of transgressing morality has surged since the Islamist Ennahda party won Tunisia's first post-revolution elections in October.

Tunisia's revolution, which culminated in a peaceful election in October, inspired reform movements throughout the Middle East dubbed the Arab Spring uprisings.

Tunisians overthrew the autocratic ex-president Zine Abidine Ben Ali. Egypt's Hosni Mubarak and Muammar Gaddafi in Libya were also ousted.

Other high-profile "moral transgression" cases in Tunisia include a newspaper editor who was in March fined for printing a nude photo, and the trial of a private television channel director who broadcast a supposedly blasphemous film.

Tunisia's Internet agency has also been ordered to block access to porn sites.