The two main sides of Libya's civil war have agreed to resume stalled ceasefire talks on how to end months of fighting, the United Nations Support Mission in Libya (UNSMIL) has said.

The UN mission in statement on Tuesday urged both parties to "commit to fully authorising their representatives in the negotiations to enable them to complete the ceasefire agreement".

Libya's conflict pits the UN-backed government against forces loyal to Russian ally Gen Khalifar Haftar.

Gen Haftar walked out of the initial talks held in Moscow in January without signing a deal.

The UN has told backers of both sides to abide to agreements on "cessation of all forms of military support permanently".