The UN special envoy for Libya, Jan Kubis of Slovakia, has quit just a month before crucial presidential elections in the war-torn nation -- without giving Security Council members a clear reason for his sudden departure.
"Mr Kubis has tendered his resignation to the secretary general who has accepted it with regret," UN spokesman Stephane Dujarric told reporters, adding that UN chief Antonio Guterres was "working on an appropriate replacement."
Asked for a reason for Kubis's resignation, less than a year into his tenure, Dujarric demurred, saying only: "It's a question you'll have to ask him."
"Mr Kubis has made it clear that he is not slamming the door today," Dujarric added, saying the envoy would deliver a monthly update on the situation in Libya, as scheduled, on Wednesday.
No date has been set for his departure, the spokesman said.
Libya's first ever direct presidential poll is due to take place on December 24, as the UN seeks to end a decade of violence in the oil-rich nation since a NATO-backed uprising that toppled and killed strongman Moamer Kadhafi in 2011.
The 15 members of the Security Council were informed of Kubis's resignation earlier on Tuesday. Russia's deputy envoy to the United Nations, Dmitry Polyanskiy, told reporters he had no indication of his reasons for leaving, and was seeking to find out more.
A former UN envoy for Lebanon, the 69-year-old Kubis took up the Libya post in January.
The Security Council recently split over whether to reconfigure the leadership of the global body's political mission in Libya, with several members calling for the envoy's post to be transfered from Geneva to Tripoli.
Diplomats said Kubis had been reluctant to undertake such a move.
The renewal of the UN's political mission to Libya, which should have been a formality, hit a major roadbump in September over the issue.
"Jan Kubis did not want to leave the comfort of Switzerland for Libya," a diplomat told AFP at the time on condition of anonymity. "He does have a point. He applied for a job in Geneva, and his posting is being changed midway through."
The result was a three-week tug-of-war between London, which authored a resolution to extend the mission, and Moscow, which repeatedly threatened to use its veto over the measure.
The Security Council on September 30 ultimately agreed to an extension, but only until late January.
Africa, which had stepped up pressure in 2020 for the envoy to be from the continent rather than Europe, is expected to again seek to claim the post following Kubis's departure.
His sudden exit comes a day after the close of presidential nominations for Libya's closely-watched elections.
According to Libya's electoral commission, 98 candidates including two women have submitted applications to be on the presidential ballot.
Among the most notable hopefuls are Seif al-Islam Kadhafi, son of the late dictator Kadhafi, and Khalifa Haftar, leader of the self-styled Libyan National Army in control of the country's east and parts of the south.
Also in the running are former interior minister Fathi Bashagha and Prime Minister Abdulhamid Dbeibah of the interim, UN-brokered Government of National Unity.