Soldiers and police have clashed in the last few days in southern Libya, near the country's biggest oilfield, with ethnic Tibu fighters who had been trying to smuggle in fellow tribesmen from Algeria, medics and residents said.
Up to 12 people have been killed in the fighting, which broke out on Wednesday and is symptomatic of the anarchy in Libya, where the government is almost powerless to control former rebel militias who helped oust Muammar Gaddafi in 2011 but now fight each for control and a share of oil revenues.
The fighting started in Ubari, near the El Sharara oilfield, which was shut last week because of damage to a storage facility at the Zawiya refinery in the north, which it feeds.
Residents said gunmen had attacked a police station in the town, not far from the main southern city of Sabha, after the border smuggling attempt failed. Around 27 people were wounded, hospital medics said.
Some commentators on Libyan social media websites linked the fighting to attempts by an armed opposition group from the western city of Misrata to get access to the El Sharara field after taking the capital Tripoli last month.
Libyan media have reported that envoys from Misrata-based groups have visited several areas in western and southern Libya in the past few weeks to sound out the possibility of cooperation with local groups and tribes.
Misrata, Libya's third city, is home to some of the most experienced rebel militias, as well as Libya's biggest non-oil port.
But the city lacks access to oil, Libya's only source of revenue for the $47 billion annual budget. Rival militias from Zintan, who have been expelled from Tripoli by Misrata's forces, control pipelines coming from the two southern oilfields of El Sharara and El Feel.
Members of the Tibu minority, which has complained of neglect, have blocked the El Sharara field in the past to demand financial assistance or guarantees of citizenship for Tibu who come from neighbouring Algeria or Niger.
El Sharara is jointly operated by Libya's state-run National Oil Corp (NOC) and Spain's Repsol . El Feel, which has also been blocked on occasion by other protesters, is operated by NOC and Italy's ENI.
Since a Misrata-led rebel alliance took control of Tripoli earlier this year, forcing the elected parliament and officials to move to Tobruk in the east, Western powers and Libya's neighbours have become increasingly worried that the OPEC member is sliding into civil war.
The Misrata alliance has set up a rival parliament and government, which have not been recognised by the international community.
The El Sharara field was pumping around 200,000 barrels of oil per day until the shutdown last week, and Libya as a whole was producing 870,000 bpd, according to a senior oil official.
On Sunday, Ibrahim al-Awami, head of the inspection and measurement department at the Oil Ministry, said Zawiya and El Sharara remained shut, and Libya's output was down to 700,000 bpd.
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