Haftar, whose self-styled Libyan National Army (LNA) is bearing down on the capital, Tripoli, with the backing of Egypt, the United Arab Emirates, Russian mercenaries and African troops, attended the one-day summit in the German capital despite having abandoned talks over a truce last week.

Turkey has rushed troops to Tripoli, as well as Turkish-backed fighters from Syria, to help Libya's internationally recognised government of Prime Minister Fayez al-Serraj resist eastern commander Haftar's assault.

Libya has had no stable central authority since dictator Muammar Gaddafi was overthrown by NATO-backed rebels in 2011. For more than five years, it has had two rival governments, in the east and the west, with streets controlled by armed groups.

German Chancellor Angela Merkel told reporters on Sunday that the Berlin summit, attended by the main backers of the rival Libyan factions, had agreed that a truce in Tripoli over the past week should be turned into a permanent ceasefire to allow a political process to take place.

A special committee made up of five military officials from each side will monitor the truce, she said. Foreign powers active in Libya have committed themselves to uphold an existing UN arms embargo and stop shipping weapons there, she added.

Serraj and Haftar did not meet in Berlin, Merkel said, highlighting the gulf between the two.

"We know that we have not solved all of Libya's problems today but we were aiming for fresh momentum," she said.

Haftar, the east's most powerful figure, has won backing from a range of foreign allies for an assault to capture Tripoli in the west, while Turkish support for Tripoli's effort to repel him has turned the conflict into a proxy war. More than 150,000 people have been displaced by fighting for the capital.

Haftar quit a Turkish-Russian summit a week ago and escalated the conflict on Friday when eastern oil ports were shut down. Libya's National Oil Corporation (NOC) said the shutdown was directly ordered by Haftar's forces.

On Sunday, NOC said the major southwestern fields of El Sharara and El Feel were closing after forces loyal to Haftar shut a pipeline.

The closures will cut Libya's oil output to 72,000 barrels a day (bpd) from 1.2 million bpd in just a few days' time unless the blockages are lifted, the NOC said.

Any lasting closure could hit Tripoli hard since the government relies on oil revenues to fund its budget.

German Foreign Minister Heiko Maas said Serraj and Haftar had "in general" agreed to solve the output blockage, without giving a time frame.

US Secretary of State Mike Pompeo told reporters that progress had been made towards reaching a full-fledged ceasefire in Libya's war, adding that he hoped Libyan oil facilities would reopen as a result of the talks.

Australian Associated Press