Police and protesters have clashed in the centre of Tunis after nearly a month of violent demonstrations, posing a serious challenge to the Tunisian president's two decades of iron-fisted rule.
Police fired tear gas at hundreds of protesters at a main junction, driving them to disperse into adjoining streets.
The fighting erupted hours after the interior minister was fired, a move that intensified a sense of uncertainty and questions about what is next for autocratic President Zine El Abidine Ben Ali - questions that have never been openly asked during his time in power.
The protests over Tunisia's soaring unemployment and corruption erupted after a young man tried to kill himself. They spread as social networks such as Facebook spread word of the unrest despite tight media control.
Police have repeatedly shot at demonstrators setting fire to buildings and stoning police. The government said 23 people have died but unions and witnesses put the toll at 46 or higher.
The upheaval has ravaged the nation's reputation as a stable and moderate Muslim nation and highlighted its inability to provide opportunities for its young.
It began in the centre of the country, far from the Mediterranean beaches popular with tourists, but riots were reported on Tuesday night in the Ettadhamoun district three miles west of the capital Tunis before spreading to the centre of town.
Prime Minister Mohamed Ghannouchi announced the sacking of interior minister Rafik Belhaj Kacem, and said that most prisoners arrested during the riots were being freed. He said official Ahmed Friaa would replace Mr Kacem.
Mr Ghannouchi announced two inquiry commissions to probe "excesses committed during the troubles" and "the question of corruption and faults committed by certain officials," the statement said.
Mr Kacem kept his job in a government reshuffle last month, but pressure on Tunisia's leadership has mounted as the protests took an especially violent turn.