Missiles were fired at Libya's capital Tripoli, including the city's only functioning airport, forcing authorities to divert flights to another airport to the south, government and airport officials said on Wednesday, less than a week after the UN brokered a cease-fire between rival armed groups.The source of Tuesday's missile attack was unclear and there were no casualties reported, the officials said. They spoke on condition of anonymity because they were not authorised to brief media.Mitiga International Airport posted on its Facebook page late on Tuesday that the airport was closed and all flights were being diverted to Misrata International Airport.Pilots were called on Tuesday night to fly planes out of Tripoli to Misrata so they would not be hit, said one official."This was the only option to make sure they were not destroyed after the missiles landed on the airport grounds," he said.Also on Wednesday, the UN envoy for Libya, Ghassan Salame, met with the head of the UN-backed government, Fayez Sarraj, and military commanders in the western town of Zawiya to discuss a "Tripoli security arrangement," according to the UN mission in Libya."There is readiness by the international community to deal firmly with those who manipulate or violate the cease-fire," Salame said in the meeting.He said he will meet with diplomatic missions and ambassadors to Libya later on Wednesday to "discuss the latest ceasefire violations and those behind them."Salame told a press conference after the meeting in Zawiya that there were at least 14 violations to the cease-fire agreement last week, including Wednesday's attack on the airport. He said the UN mission knows those who shelled Mitiga International Airport. He did not elaborate.The missile attack followed recent fighting in Tripoli between rival armed groups, which left at least 61 people dead. A cease-fire has been in place since last week.* Sign up to News24's top Africa news in your inbox: SUBSCRIBE TO THE HELLO AFRICA NEWSLETTERFOLLOW News24 Africa on Twitter and Facebook. Clashes in Tripoli erupted August 26 when militias from Tarhouna, a town south of Tripoli, attacked southern neighborhoods of the capital, prompting militias supporting the UN-backed government in Tripoli to come to the city's defence. The fighting has killed 78 people and wounded 216 including eight children and six women, according to the Health Ministry.Separately, the extremist Islamic State group on Tuesday claimed responsibility for an attack on the headquarters of Libya's national oil company in the capital Tripoli that killed two people and wounded at least 10 others. The attack was the first of its kind that targeted the country's oil firm.Islamic extremists expanded their reach in Libya after the 2011 uprising plunged the country into chaos and toppled and later killed longtime ruler Muammar Gaddafi.ISIS was driven from its main stronghold, the coastal city of Sirte, in 2016 and fled inland.Libya is currently governed by rival authorities in Tripoli and the country's east, each of which are backed by an array of militias. Other armed groups have carved out fiefdoms across the country, with many profiting from smuggling and extortion.