Tunisian security forces fired tear gas on Monday to disperse hundreds of protesters demanding jobs and a share in revenue from gas and oil companies, as weeks of unrest over jobs and funding in the country's southern provinces escalated into violence.

Protesters briefly forced the closure of the Vana pumping station, one of several oil and gas stations affected over the weekend, after the army allowed an engineer to shut it to avoid a confrontation.

The defence ministry warned that it would use force to protect and retake southern oil and gas facilities, and clashes broke out at Vana on Monday when the military took back control to restart the pump, two witnesses said.

"One must understand that attempting to enter by force an installation protected by the army ... is not a peaceful act. It's an attempt to enter by force and it requires a reaction," defence ministry spokesman Belhassen Oueslati told Express FM radio on Monday.

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Protesters forced over the weekend the closure of two oil and gas pumping stations, where Italy's ENI SpA, Austria's OMV AG and France's Perenco operate, and where Prime Minister Youssef Chahed had already deployed troops.

Tunisia is a small oil producer with an output of about 44,000 barrels per day.

But the closures represent a clear challenge to the authority of Chahed's government as it tries to enact economic reforms demanded by international lenders and consolidate Tunisia's transition to democracy six years after an uprising forced long-term ruler Zine El-Abidine Ben Ali out of office and into exile.