Libya’s oil production and exports have almost ground to a halt as the increasingly unpredictable Gen Khalifa Haftar, the military leader in the country’s east, ignores international calls to seek a negotiated political settlement to the civil war.

World leaders had convened in Berlin on Sunday to endorse plans to entrench, monitor and enforce a ceasefire intended as a precursor to the disarming of militias and political talks in Geneva to build a reunified government, and a fair distribution of oil revenues between the east and west of the country.

But Haftar, who has been seeking to oust by force the UN-recognised government of national accord (GNA), based in Tripoli, since April, showed no sign of relenting, instead ramping up the economic pressure on the GNA by shutting down oilfields.

In a sign the situation was deteriorating, the Libyan National Oil Corporation (NOC) reported that forces directly under the instruction of Haftar had blocked oil exports from Brega, Ras Lanuf, Hariga, Zueitina, and Sidra ports.

“The blockade instructions were given by Maj Gen Nagi al-Moghrabi, the commander of Petroleum Facilities Group appointed by the Libyan National Army, and Col Ali al-Jilani from the LNA’s Greater Sirte Operations Room,” the NOC said.

It said pipelines had been blocked linking the giant Sharara oilfield to the Zawiya oil terminal and El Feel oilfield to the Mellitah terminal. Libyan oil production was expected to collapse to 72,000 barrels a day, the lowest level since 2011.

Unofficial diplomatic reports from Russia said Haftar had refused to sign the Berlin agreement, and for parts of the summit had turned off his phone, before leaving early.

The Turkish president, Recep Tayyip Erdoğan, an opponent of Haftar, said it was significant that the general had not signed the agreement. He said Turkey would do whatever was necessary if Haftar and his so-called Libyan National Army (LNA) did not abide by the agreement. He has already sent former fighters from Syria to help protect the GNA government, which is led by the prime minister, Fayez al-Sarraj.

Haftar did not meet Sarraj in Berlin, and neither leader was present at the “family photograph” attended by 11 world leaders, nor at any signing ceremony. Social media posts issued by supporters of Haftar’s LNA instead spoke about recruiting 4,000 extra volunteers.

The first direct test of any Berlin accord would be whether Haftar’s forces abided by the ceasefire, and sent delegates both to a UN ceasefire committee and political talks in Geneva aimed at setting up the unified government.

The eastern forces, backed by local tribes, link the reopening of the ports to a demand that more oil revenues are distributed to the east and south of the country. The Berlin conference said future distribution of oil revenues could be addressed in any political talks.

Sarraj rejected concessions to the east at this point, saying: “Our long experience in dealing with Haftar reinforces that he will seek power at any cost.” He said it would be a catastrophe if the dispute was not settled soon.

The agreements at the Berlin conference are largely contingent on the two sides wanting to implement a ceasefire rather than seek military victory.

Erdoğan defended his troop presence in Libya, claiming the Russian security company Wagner had 2,500 security personnel in the country working for Haftar. He said: “It is not only Wagner; there are also 5,000 soldiers from Sudan there. In addition to this, there are soldiers from Chad and Niger. The Abu Dhabi administration takes from whatever sources they can find.” He claimed there were also Sudanese mercenaries whose funding was being provided by the United Arab Emirates.

The UAE’s foreign minister, Anwar Gargash, moved to challenge reports that his country, Haftar’s chief military backer, was discouraging the general from winding down his military operations, tweeting that the UAE backed the Berlin outcome.

The crown prince of Abu Dhabi and minister of defence of the UAE, Mohammed bin Zayed al-Nahyan, declined to attend the conference, instead holding only a bilateral meeting with the German chancellor, Angela Merkel, on Saturday.

The EU foreign affairs chief, Josep Borrell, said on Monday that the EU was preparing to revive Operation Sophia to police a UN ban on the import of arms into Libya. Without going into details, he said diplomats would draw up proposals to present to EU ministers.

The relaunch of the operation is another sign that the EU is determined to be more involved in solving the Libyan crisis. The mandate for the operation is due to expire in March, including aerial surveillance, but it was suspended as a naval mission last March after the then Italian interior minister, Matteo Salvini, objected to rescued migrants coming to Italy.

Borrell said that the EU operation had never been solely focused on migration, but also to enforce a UN arms embargo in Libya. The operation would be “reorientated” to the agreement in Berlin this weekend, he said. “It doesn’t mean that [the revived operation] is not going to take care of the migrant issues, but the important thing to be clear is that we are not going to revive Operation Sophia for that reason, but for the urgent need of arms control.”

Proposals to reboot Operation Sophia are likely to be presented to ministers in February, by which time the UK will no longer take part in EU meetings.

Additional reporting by Jennifer Rankin in Brussels