Protesters demanding jobs in Tunisia's energy sector blocked roads with blazing tyres on Sunday after the arrest of an activist, as security forces responded with tear gas.
For weeks, demonstrators have erected a protest camp in the southern Tataouine region demanding authorities make good on a 2017 promise to provide jobs in the gas and oil sectors to thousands of unemployed.
They have blocked roads around the El-Kamour pumping station to prevent tanker trucks from entering the facility but so far the protest had been largely peaceful.
On Sunday, however, it turned violent after the arrest of an activist "wanted" by the authorities, the governor of Tataouine, Adel Werghi, told a local radio.
The activist, arrested the night before, was identified as Tarek Haddad, the spokesman for the protesters.
An AFP correspondent said demonstrators set tyres ablaze in Tataouine and pelted security forces with stones demanding his release.
Security forces responded with tear gas and the situation remained tense in the afternoon, with intermittent clashes taking place.
The governor said it was "illegal" for protesters, who have been demonstrating for more than a month, to block roads with tents "which they have set up in the middle of streets".
In 2017, protesters had blockaded the El-Kamour pumping station for three months demanding jobs.
The sit-in ended after the employment minister signed a deal with representatives of the protesters, brokered by the powerful Tunisian trade union confederation UGTT, pledging to invest 80 million Tunisian dinars a year (almost $28 million) in Tataouine.
The UGTT said the promise was never kept.