Bernardino Leon tells Al Jazeera that a political agreement is the only way forward as rivals meet for talks in Rabat.
An official from Libya’s UN-recognised government in Tobruk has said that its forces have shot down a warplane flown by Libya’s Dawn, the armed group allied with the rival legally-installed government in Tripoli.
Mohammed al-Masri said the plane was downed on Monday after it bombed Zintan, a mountainous western town supportive of the Tobruk administration.
Forces in Zintan region said they had shot down the fighter jet while it was trying to attack the local airport.
“Two pilots of the Dawn jet downed this morning have been found,” said Omar Matooq, spokesman of Zintan airport, the Reuters news agency reported.
“One of them was found dead after suffering burns. The other pilot is alive and has been arrested.”
An official in the Tripoli administration said the plane had crashed due to a technical fault.
Meanwhile, army spokesman Ahmed al-Mesmari said the the Tobruk-based government launched an air strike targeting fighters in the city of Tarhouna on Monday.
He said the strikes prompted retaliatory attacks that killed four civilians, including a woman whose hands were cut off.
Four years after NATO warplanes helped dislodge longtime leader Muammar Gaddafi, Libya has descended into chaos, with the two rival governments fighting for control, both fielding armies of former rebel fighters and air forces that bomb rival territory.
The country also faces the rise of an affiliate of the Islamic State of Iraq and the Levant (ISIL) group.
The UN has been trying to persuade the rival governments to form a unity cabinet, but the fighting and internal divisions on both sides have undermined the dialogue.
On Sunday, Bernardino Leon, UN special envoy, said talks in Morocco where negotiators are trying to form a government from both sides would be extended for two more days despite the clashes.
Diplomats say they accept that moderates attending the talks from both sides will face difficulties in persuading hardliners to accept any deal.