Forces loyal to eastern Libyan commander Khalifa Haftar have launched attacks at ports in Libya's oil crescent and clashed with guards who control the terminals, according to a spokesman and witnesses.
Petrol Facilities Guard (PFG) spokesman Ali al-Hassi said on Sunday afternoon that Haftar's forces attacked at Zueitina, Ras Lanuf, and Es Sider ports in the east of Sirte, as well as the nearby town of Ajdabiya, and that clashes were ongoing.
A port engineer confirmed that Haftar's forces had entered the oil ports of Ras Lanuf and Es Sider, Libya's largest, and said one of the storage tanks at Es Sider had been set alight in the clashes.
The PFG also said it would reopen the Zueitina Port, but Haftar's forces, known as the Libyan National Army (LNA), mobilised in the area leading to fears of a struggle for control.
Meanwhile, the LANA news agency loyal to the internationally recognised parliament reported spokesman Colonel Ahmad Mesmari as saying on Sunday that Haftar's forces took control of both ports.
The ports have been closed since late 2014, but the PFG recently struck a deal with the UN-backed government in Tripoli to reopen them and attempt to resume exports.
Haftar and other power brokers in the east have opposed the UN-backed Tripoli-based government, preventing it from extending its authority to eastern Libya.
Ras Lanuf and Es Sider were badly damaged earlier this year in attacks by Islamic State of Iraq and Levant (ISIL, also known as ISIS) fighters based in Sirte.
The attacks on Libya's major oil ports by Haftar, who opposes the U.N.-backed Government of National Accord (GNA), pushes the North African state towards a broader battle over its oil resources and disrupts attempts to restart production.
Armed conflict, political disputes and militant attacks have reduced Libya's oil production to about 200,000 barrels per day (bpd) from 1.6 million bpd it was producing before an uprising and fall of Muammar Gaddafi in 2011.
Haftar's move to take over the oil ports, according to Libya analyst Mattia Toaldo of the European Council on Foreign Relations, "was widely expected".
"This area of the oil crescent is where militias, after the fall of Gaddafi, have fought over and over again," he said, speaking to Al Jazeera from London.
The fighting around the oil ports underscores the fragility and volatility of the unity government in Libya, a country with rival parliaments and rival governments.
"Haftar has never recognised the government in Tripoli. He's loyal to the house of representatives [in Tobruk], which, because things are complicated in Libya, is also internationally recognised," said Toaldo.
Haftar, a former army general who has been a divisive figure in Libya since Gaddafi was toppled, has resisted attempts to integrate him into a unified armed forces and overcome divisions between the east and west regions.
Many in western Libya and Tripoli criticize Haftar as a former Gaddafi ally bent on establishing a military dictatorship, but he has become a political figurehead for many in the east who feel abandoned by the capital.