Libyan peace talks that the UN says could be the "moment of truth" for the war-wracked country have made progress since resuming in Morocco, a participant told AFP on Saturday.

"We have reached agreement on seven of the nine points in the political accord," said Ashraf al-Shehh, political adviser to the General National Congress in Tripoli.

Libya, torn apart since dictator Moamer Kadhafi's ouster in 2011, has two rival administrations -- the GNC and an internationally recognised government based in Tobruk in the far east.

Shehh said the two outstanding issues relate to military and state appointments during an interim period and how to appoint members of the High Council of State.

He reported intense consultations to complete the negotiations before September 20.

When the talks resumed on Thursday, UN peace envoy Bernardino Leon was upbeat.

"We are starting a new round of talks in the Libya process, which we hope will be the final round, the moment of truth for the parties," he said in Skhirat near the Moroccan capital.

"We are very hopeful that they will understand that this deadline of 20th of September must be the last one, must be the one that will allow Libya to get out of this crisis."

Leon's peace plan calls for a unity government deal by September 20, ahead of the UN General Assembly, with the government coming into force a month later.

A two-year transitional government would then work towards organising parliamentary elections.

Leon said Thursday a deal on creating a unity government could be reached "in the coming days", but that difficult work remained before a final accord.

The rising influence of the Islamic State jihadist group and Libya's emergence as a smuggling hub for migrants risking their lives to cross the Mediterranean have added urgency to the long-running and often derailed UN talks.