One person was killed after a national guard vehicle ran him over, and dozens others were injured after protesters clashed with security forces in southern Tunisia, raising fears of mounting social unrest in a region rocked by weeks of protest.

The young protester was killed on Monday after a national guard's vehicle "accidentally" ran him, the health ministry said.

"The health ministry announces the accidental death of a young man, (run over) by the national guard. He was a protester," the ministry told AFP news agency.



The death comes as tensions have risen between protesters, who are demanding jobs and a share in revenue from local gas and oil companies, and security forces outside the El Kamour oil and gas pumping station.

Protesters have been camping outside the desert installation in the Tataouine region for around a month, blocking trucks from entering.



Earlier on Monday, security forces fired tear gas at the demonstrators as they tried to storm the facility, local radio said, with another protest later reported in the city of Tataouine some 100 km away.



The head of Tataouine hospital, Ibrahim Gharghar, said "around 50 injured" people were admitted, including one who was hit in the eye by a tear gas canister.



The death of the demonstrator came two days after soldiers fired warning shots in El Kamour to deter protesters.



It was the first escalation since President Beji Caid Essebsi said earlier this month the army would protect key economic installations from being disrupted by protests over social and labour issues.

READ MORE: Tunisian forces clash with protesters at oil fields

Late on Sunday, the defence ministry warned in a statement that the army would use force against anyone who tried to enter those installations.

The statement warned "all citizens of legal proceedings in the case of clashes with military or security units" and of possible casualties in "the case of a gradual escalation of use of force".



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