At least 200 people were injured as Tunisians demanding jobs and economic development clashed with police, medical sources said, in the latest unrest to hit the country that spawned the Arab uprisings.
Officers on Wednesday fired teargas and birdshot to disperse crowds who rallied for a second day in Siliana, a city in Tunisia's economically deprived interior on the edge of the Sahara desert, witnesses said.
Tunisia ousted its president Zain al-Abidine Ben Ali last year, setting off a wave of uprisings that toppled rulers in Egypt, Libya and Yemen and inspired the revolt in Syria.
Its new, elected Islamist-led government has since struggled to revive the economy in the face of a decline in trade with the crisis-hit eurozone and disputes between secularists and Salafi Islamists over the future direction of the North African state.
A medic from Siliana Hospital who did not wish to named said more than 200 people had been injured in the clashes.
David Thomson, a journalist from France 24 television confirmed he had been hospitalised for wounds from birdshot apparently fired by riot police.
Many protesters called for the resignation of local officials, saying the authorities had failed to release development funds for their region.
State television said that at least 80 people were injured and that residents blocked the entrances to the city, setting tyres alight on roads.
Iyed Dahmani, a politician from the Republican Party in the town, said the National Guard - an interior ministry-run security force - had deployed tanks to help restore order.
The protests were the fiercest since Salafi Islamists attacked the US embassy in Tunis in September over an anti-Islam film made in California. That violence left four people dead.
Prime Minister Hamadi Jebali has accused both Salafis and liberal elites of harming Tunisia's economy and image through their conflict with each other. His Ennahdha party has tried to present itself as a middle way between liberals and Salafis.
The World Bank on Tuesday approved a $500m loan to Tunisia to help it recover from the uprising, with another $700m loan coming from other donors.
The loan, the World Bank's second since the revolution, aims to support Tunisia's economic recovery by providing funds to improve the business and financial sectors and reform social services.