UN-backed talks aimed at paving the way for elections in Libya in December missed a deadline and extended into a fifth day on Friday with delegates struggling to agree, Reuters reported.
The meeting of the Libyan Political Dialogue Forum near Geneva was due to establish the constitutional basis for presidential and parliamentary elections by July 1.
But delegates and UN officials said they could not agree among themselves on several proposals circulating, prompting organisers to extend the talks originally planned to last four days.
The elections would be a key part of international efforts to bring stability to Libya, which has been in turmoil since a 2011 NATO-backed uprising against Muammar Gaddafi.
A UN-led peace process brought a ceasefire last summer after fighting between rival factions paused and then a unity government was formed.
The talks in Switzerland follow on from an international conference in Berlin last week.
The United Nations envoy for Libya, Jan Kubis, said on Monday that leaving Switzerland without a decision this week was "not an option" given the timeframe.
"He's really pushing for consensus to be achieved on the way forward to find that Constitutional basis that will allow the country to hold the scheduled elections on 24 December," UN spokesman Rheal LeBlanc told a briefing on Friday.
On Thursday, Kubis described that day's session as "difficult" and urged delegates to refrain from "disrespectful behaviour and personal attacks", without elaborating.
A UN live feed of the talks streamed the discussions of the 75 delegates earlier in the week has since halted.
However, one delegate, Lamees Bensaad, said he still thought agreement could be reached.
"I'm optimistic and look forward to consensus," she said.
Moves towards a political solution in Libya accelerated after eastern commander Khalifa Haftar's 14-month assault on Tripoli collapsed last summer.
A formal ceasefire was agreed in October and the next month the participants in the UN peace dialogue set a date for elections and agreed to create a new interim government.
However, major risks persist with myriad armed groups holding power on the ground.
Haftar was backed by the United Arab Emirates, Russia and Egypt in his Tripoli offensive. The internationally-recognised Tripoli government was supported by Turkey, which ultimately helped it repel the assault.