Picture shown is for illustrative purposes only.

Eastern Libyan forces closed down major oil ports, a spokesman for an oil protection force allied to eastern-based commander Khalifa Haftar said on Friday, escalating tensions before an international Libya summit to discuss the country's conflict.

Libyan leaders fail to agree on ceasefire

Tribesmen allied to Haftar had earlier stormed one port, the Zueitina terminal.

Libyan commander Khalifa Haftar poses for a photograph in Athens, Greece, on Friday. Costas Baltas/Reuters

Libya will lose at least 700,000 barrels of oil exports per day as a result of the closure, a source at state oil firm NOC said.

The spokesman for Haftar's force, Ahmed Mismari, confirmed exports had been stopped and said it was the work of the "Libyan people".

The move marks a setback for efforts to end a conflict in the OPEC oil producer. Germany is to host a summit in Berlin on Sunday to which Haftar and his main rival, the internationally recognized prime minister Fayez Al Serraj, have been invited together with their various foreign backers.

Central security support force carry weapons during the security deployment in the Tajura neighbourhood. File photo/Reuters

Hours earlier, tribesmen from areas in eastern and central Libya controlled by Haftar's Libya National Army (LNA) stormed the Zueitina oil port and vowed to shut down all other ports in the region.

In a statement posted online on Thursday, tribal leaders called for Libya's oil terminals to be shut and accused the internationally recognised government in Tripoli of using oil revenue to pay foreign fighters.

Scores of protesters erected a large tent outside the Zueitina terminal, where they read a statement saying they plan to shut all oil terminals in eastern Libya.

Port engineers in the other three eastern terminals — Brega, Ras Lanuf and Es Sider - told Reuters that the ports were still open and receiving oil.

NOC had earlier warned against closing the terminals.

A member of forces allied to Libya's government stands near a destroyed  military vehicle in Gharyan. File photo/Reuters

"The oil and gas sector is the lifeblood of the Libyan economy ... they should not be used as a card for political bargaining," NOC Chairman Mustafa Sanalla said in a statement.

"Shutting production and export of oil will have serious and easily predictable consequences for the Libyan economy," he said.

Eastern Libya and part of the south are controlled by the LNA, which has been trying to take Tripoli, home to the U.N.-backed Government of National Accord.

Germany and the United Nations will push the rival camps to agree a truce.

The Tripoli-based NOC has sought to stay out of the conflict but faces pressure from the LNA, which controls most of the country's oil ports. NOC channels oil and gas revenue through the central bank, which mainly works with the Tripoli government though it also pays some public servants in the east.

Reuters