Tunisia outlaws Friday protests
Authorities in Tunisia have banned protests planned by rival Islamist groups for Friday, in order to control some of the worst violence seen since last year's revolution.
Since Monday hard-line protesters have clashed with police.
A young man was shot and killed in the disturbances, and police stations were set ablaze in the unrest, that has seen about 100 people injured.
The authorities have imposed a curfew in affected areas, including Tunis.
The Ministry of Interior announced the ban in a statement, and a government spokesman told AFP news agency: "The law will be applied against all acts of violence... some calls for violence are circulating on Facebook."
Since the overthrow of Mr Ben Ali's secular rule, Islamist parties have experienced a resurgence.
The moderate Ennahda Party, which was banned under Mr Ben Ali, now dominates the political system.
Hard-line groups, including those that follow Salafist Islam, have staged a number of demonstrations over the past year, demanding the introduction of Sharia law in Tunisia.
Followers of Salafist Islam believe in a very literal and strict adherence to Islam, as it was first practised 1,400 years ago.
This week's protest was against an art exhibition that included a portrayal of a nude woman.
Artists staged their own protest in response.
The Ennahda party also called for its own "peaceful" rally on Friday.
On Wednesday Ben Ali, who has been living in exile in Saudi Arabia since he was ousted, was convicted in absentia and sentenced to life in jail for killing demonstrators in last year's uprising.