Renewed clashes in Tunisia left at least three people killed and a dozen injured late Saturday, the Tunisian Interior Ministry said, dpa reported.
The demonstrators were killed in violent clashes in Tunis, the ministry said.
Until late in the evening, shots were exchanged between protesters and police in central Tunis, witnesses said. Helicopters were seen circling over the capital.
More than 100 people were arrested for arson and property damage, the ministry said.
The demonstration against the country's interim government, which many fear has been compromised, began peacefully a day earlier, but government sources said young hooligans used it as an opportunity for mischief. On Friday, another protester was reported killed.
Police responded to stones thrown by protesters with tear gas and a central avenue was blocked to traffic.
A journalist for the Essahafa newspaper reported direct confrontations with police after they accused him of filming them, drawing knives on him and demanding his mobile phone.
Popular protests in Tunisia led to the ouster of president Zine el-Abidine Ben Ali last month, setting off broader ongoing pro- democracy demonstrations against leaders across the Middle East and North Africa.