The UN Support Mission in Libya (UNSMIL) issued a warning on Tuesday about the unfolding security situation in the capital, Tripoli, where armed groups are being mobilised.
"This creates tension and increases the risk of clashes that could spiral into conflict," said UNSMIL. "Any disagreements on emerging political or military matters should be resolved through dialogue, particularly at this stage when the country is navigating through a difficult and complex electoral process that should usher in a peaceful transition."
Images posted online early on Tuesday showed tank and pickup trucks mounted with machine guns in Fornaj district, where some roads were blocked by armed men. Schools and the University of Tripoli closed as a precaution but there were no firefights, residents told AFP.
Libya's presidential election is scheduled to take place on 24 December, followed by a parliamentary election in a few weeks' time. However, it looks increasingly likely that the former, if not both, will be postponed.