Police fired tear gas and rubber bullets to disperse a second anti-government protest in the central Tunisian town of Sidi Bouzid, birthplace of last year's revolution.
Some 800 demonstrators furious at police intervention against a protest earlier in the day threw stones at security forces who again replied with rubber bullets and tear gas.
On Thursday morning hundreds of demonstrators demanding the resignation of the Islamist-led government had tried to force their way into the provincial government headquarters, before the police fired tear gas and warning shots into the air.
The protesters broke through the entrance to the compound, but when the shots and tear gas were fired, the panicked crowd scattered, an AFP journalist said.
One person wounded by a rubber bullet and four others affected by the tear gas were taken to hospital, an official there said, adding that none of them was seriously hurt.
The demonstrators had been chanting anti-government slogans such as "The people want the regime to fall!" accusing the ruling elite of "hypocrisy" and demanding the right to work.
Several opposition groups took part in the protest, including the Republican Party, the Tunisian Workers Party and Al-Watan, as well as political independents.
"The people's demands for an improvement in their quality of life are becoming more and more insistent, but unfortunately the government is not there to serve the people," Mohammed Ghadri, a member of the Republican Party, told AFP.
A similar incident took place at the end of June, when protesters angered over their living conditions attacked the same building, hurling rocks and burning tyres, with police firing tear gas to disperse them.
The Tunisian Workers Party denounced the forceful tactics used by the police on Thursday and reiterated its support for the protesters' demands, including the dismissal of the provincial governor, the head of the national guard and the public prosecutor.
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Sidi Bouzid is where the uprising began that eventually toppled former dictator Zine El Abidine Ben Ali and touched off the Arab Spring, when a street vendor immolated himself in December 2010 in protest over his own precarious livelihood.
The town is located in a particularly marginalised region, and little has improved since the revolution, according to analysts.
"The residents of Sidi Bouzid live in very difficult conditions, especially with the water and electricity cuts seen recently," said political expert Ahmed Manai.
"These protests were to be expected."
Poor living conditions, including high youth unemployment, were a driving factor behind the revolution.
Despite signs of an economic recovery this year, many people remain frustrated by the government's failure to improve their social circumstances, which has led to strikes and confrontations with the police.
The forceful disruption of Thursday's protests came amid heightened criticism of the government by opposition and civil society groups, which accuse it of increasingly authoritarian and Islamist tendencies.
Several NGOs have accused Ennahda, which leads the ruling tripartite coalition, of seeking to curtail freedom of expression, most recently with a draft law to criminalise offences against "sacred values" that could carry a two-year jail term.
Another controversy has flared up over a proposed article in the new constitution that refers to the "complementarity" of men to women rather than their equality.
Around 200 protesters from different opposition groups gathered outside the National Constituent Assembly in Tunis on Thursday to denounce the proposal.
Some of them tried to force open the entrance to the parliament but were stopped by the police.