UN Secretary General Ban Ki-moon said Monday he was "extremely concerned" about increasing violence and civilian casualties in the Libyan capital Tripoli.
In a statement, Ban called on all parties to refrain from violence to achieve political objectives.
"The Secretary General reiterates the urgent need for dialogue among all Libyan actors to agree on a peaceful way forward for the political transition process," Xinhua quoted Ban as saying.
Armed clashes broke out at Libya's international airport in Tripoli early Sunday, leaving nine people dead and 25 others injured.
The fighting was believed to be between armed Islamist groups and militia from Libya's southwestern city of Zintan. Both sides claimed on their social networking websites that they had taken control of the crucial air hub.
All flights to Tripoli for the next three days have been suspended.
British Airlines, Egypt Air, Tunisair and Turkish Airways have cancelled their flights to and from the airport, while the Libyan Afriqiyah Airways has redirected all flights arriving in Tripoli to Misrata.