The Tunisian government has imposed a night-time curfew in the capital, Tunis, and surrounding regions.
It comes after violent protests in several districts of the capital, with riot police firing tear gas at demonstrators.
Officials say at least 23 people have died across the country since the unrest began late last year.
The protesters say they are angry about rising food and fuel prices, high unemployment and corruption.
Earlier on Wednesday, President Zine El Abidine Ben Ali dismissed his interior minister in an attempt to stem the unres
