Eastern Libya ports controlled by Libyan National Army (LNA), commanded by Khalifa Haftar, shut down oil exports, slashing national crude output by more than half and ramping up tensions ahead of a summit in Germany to discuss the country’s conflict. The dramatic move came as Germany and the United Nations try to persuade Haftar at the Berlin summit on Sunday to halt his nine-month campaign to take Tripoli, seat of the Government of National Accord (GNA), headed by Fayez al-Sarraj. Tribesmen in areas controlled by the LNA on Friday stormed the eastern Zueitina oil export port and announced the closure of all terminals under LNA control, reported Reuters. LNA spokesman Ahmed al-Mismari later told reporters that the “Libyan people had closed the oil ports.” Analysts said the closure of oil ports would not have been possible without the blessing of the LNA leadership. A source in the National Oil Company (NOC) said the LNA and an eastern oil protection force had ordered the closure of the ports. The oil protection force confirmed exports had been stopped. Libya’s oil production was an estimated 1.3 million barrels a day before the closures. The tribesmen allied with Haftar earlier accused the Tripoli government of using oil revenues to pay foreign fighters - a reference to Turkey’s decision to send soldiers and fighters from Syria’s war to western Libya to help the GNA fend off the LNA campaign. The head of the eastern Zouaya tribe told AFP that blocking exports would "dry up the sources of funding for terrorism via oil revenues". The tribes also called for the "immediate" closure of the Mellitah, Brega and Misrata pipelines. NOC chairman Moustafa Sanalla said the oil and gas sector is "vital" for the Libyan economy, as it is the "single source of income for the Libyan people". "The oil and the oil facilities belong to the Libyan people. They are not cards to be played to solve political matters," he added. Libya’s oil sector, which brings in almost all of the states revenues, has frequently been the target of attacks. Sanalla said the consequences of exports and production being shut down for an extended period could be devastating. "We face collapse of the exchange rate, a huge and unsustainable increase in the national deficit, the departure of foreign contractors, and the loss of future production, which may take years to restore," he said. The ports closure mark a setback for the Berlin conference on Sunday where Haftar and Sarraj are expected. The one-day summit is the latest in a series of failed conferences and negotiations to stabilize Libya.