The UN Security Council on Saturday welcomed Libyan peace negotiations held in Geneva this week but warned the North African state it would consider sanctions against anyone undermining the country's security and stability.

Libyan factions agreed to continue United Nations-backed negotiations in the Swiss city next week over ending the country's political crisis.

Key representatives from a self-declared government based in Tripoli stayed away but in a possible sign of movement, its main armed groups battling forces of Libya's recognized government declared a ceasefire.

"The members of the Security Council supported the resumption of another round of talks in Geneva next week and strongly urged all relevant Libyan stakeholders to attend," the 15-nation council said in a statement. It added that it welcomed the ceasefire announcements.

The council cautioned that its Libya sanctions committee "is prepared to sanction those who threaten Libya's peace, stability or security or that obstruct or undermine the successful completion of its political transition."

Nearly four years after a NATO-backed revolt ousted Muammar Gaddafi, Libya is in turmoil with two rival governments and two parliaments backed by allied armed factions who Western governments fear may drag the country into civil war.

The UN talks are aimed at forming a unity government, ceasing hostilities and putting a transition to democracy on track. But the Tripoli-based forces complained this week that the process had been rushed and said they would vote on Sunday whether to go to Geneva.

Fighting over the country's oil infrastructure has closed two major oil ports in the east and slashed Libya's oil output to around 300 000 barrels per day from the 1.6 million bpd produced before the civil war toppled Gaddafi in 2011.