Protesters have shut down two key Tunisian phosphate mines in a weeks-long dispute over jobs, a mining company official said on Saturday.
The mostly unemployed university graduates blocked the entrances of sites in the central region of Gafsa to demand work, Ali Ouchetti, spokesman for the Gafsa Phosphate Company (CPG), told AFP.
"Production and transport of phosphates has been totally halted since yesterday (Friday) at the Metlaoui site because of demonstrations by dozens of unemployed" who stopped a bus carrying workers from entering the site, he said.
Protesters also prevented trucks carrying phosphate from leaving another site at Mdhilla, 15 kilometres (10 miles) to the south, where production had been halted for a week, he added.
Similar protests in August prompted government intervention, and the CPG agreed to run a competition to hire hundreds of graduates.
"We are protesting again after negotiations collapsed on Wednesday at the Ministry of Energy and Mines", said protest leader Ahmad al-Jdidi.
The CPG, one of the world's top phosphate producers, is the biggest employer in Gafsa, one of Tunisia's poorest areas.
The region witnessed an uprising in 2008 that was bloodily repressed by the regime of former dictator Zine El Abidine Ben Ali, which was toppled by a revolution in 2011.
In five years, Tunisia's phosphate production has fallen by 60 percent, Prime Minister Youssef Chahed said in late August. In June, President Beji Caid Essebsi said that had cost the country $5 billion (around two billion euros).
Tunisia is battling high unemployment and has been hit by a spate of labour protests and also jihadist attacks.
The government announced last week that British energy firm Petrofac would resume operations at a major gas plant that had been shut down since January by workers demanding permanent contracts.