Tripoli - The UN called on Friday for Libya's warring factions to resume peace talks "before it is too late" after its envoy to the violence-plagued state met with rival camps.UN envoy Bernardino Leon, who held talks for the first time with retired General Khalifa Haftar, said "time was running out" to tackle the country's political and security crises."Libyans need to unite and work towards solving their differences if they want to save their country," Leon was quoted as saying in a statement issued on Friday, a day after his meetings. Leon also met with representatives of Libya's internationally recognised government in Tobruk and with rival officials in Tripoli, the statement added. Three years after dictator Muammar Gaddafi was toppled and killed in a Nato-backed revolt, Libya is awash with weapons and powerful militias, and run by rival governments and parliaments.Haftar, a controversial figure, launched a May offensive against mainly Islamist fighters in control of the second city of Benghazi.He was initially accused by Libya's internationally recognised government of carrying out a coup but relations have since thawed as Haftar's fighters and state forces jointly battle militias. Libya's parliament, which took refuge in the remote east after fighters from the predominantly Islamist Fajr Libya militia stormed the capital in August, has asked Haftar and other retired officials to be officially reinstated into the army.With no early end in sight to the violence, the UN has postponed peace talks that were due to take place Monday.Also on Friday, a rocket attack targeted the Tripoli headquarters of a private television station close to Islamist factions, causing damage but no casualties.Al-Nidaa television said its offices had been hit by two rocket-propelled grenades but vowed that the attack would not force the channel off air.