A summit in Berlin, Germany bringing together foreign powers backing rival camps in Libya has called for all parties to refrain from hostilities against oil facilities, a draft of the final communiques showed on Sunday.

The draft also recognizes Tripoli-based state oil company NOC as the sole legitimate entity allowed to sell Libyan oil, according to the draft, which will be discussed at the summit.

The call comes after tribesmen allied to eastern commander Khalifa Haftar shut down all oil ports in eastern Libya.

On Sunday,countries attending the international peace summit for Libya struggled on to draw Haftar back into diplomacy, days after he quit talks and his allies shut down more than half of Libya's oil output.

Haftar, whose forces are bearing down on the capital Tripoli with the backing of Egypt, the United Arab Emirates, Russian mercenaries and African troops, was expected to attend the one-day summit despite having abandoned talks last week.

Turkey has rushed troops to Tripoli to help an internationally recognized government resist Haftar's assault. Up to 2,000 Turkish-backed fighters from Syria's civil war have also joined the battle, a U.N. official said on Saturday.