People taking part in the unrest, which has lasted for nearly a month, say they are angry at lack of jobs and investment, but officials say the rioting is the work of a minority of extremists intent on damaging Tunisia.

A leading opposition figure urged President Zine Al-Abidine Ben Ali to order a cease-fire to prevent further bloodshed.

The government had earlier issued a statement saying two people were killed when police fired in self-defense during overnight clashes in the town of Thala, about 200 km southwest of the capital, near the border with Algeria.

In a later statement it said three people injured in the Thala violence had since died of their injuries and that three people had been killed in separate disturbances in the nearby town of Gassrine on Sunday.

"Several government buildings in Gassrine were attacked by groups who set fire to and destroyed three banks, a police station and a filling station and set fire to a police vehicle," the statement said.

"The police fired in the air but the crowds continued and the police acted out of legitimate self-defense, which led to three deaths."

Two witnesses in the town of Rgeb, 210 km west of Tunis, said three people there, including one woman, were killed in clashes with police on Sunday.

Government officials did not respond to phone calls from Reuters seeking comment on the casualties.