UN special envoy for Libya has quit just a month before crucial presidential elections in Libya.

UNITED NATIONS (AFP) - The UN special envoy for Libya has quit just a month before crucial presidential elections in the war-torn nation without giving Security Council members a reason, a spokesman for the world body said Tuesday.

Asked for a reason for Jan Kubis s resignation, less than a year into his tenure, UN spokesman Stephane 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, while UN chief Antonio Guterres was looking for a replacement, 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.

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 transferred from Geneva to Tripoli.

Diplomats said Kubis was 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 road bump 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 applied to be run.

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.

Khadafi has been wanted by the International Criminal Court in The Hague for crimes against humanity since the 2011 uprising against his father.

The prosecutor of the ICC, Karim Khan, told the Security Council Tuesday he will visit Libya early next year to talk to all sides about investigating crimes committed during the years of upheaval.

"This joint quest to narrow impunity for genocide or crimes against humanity, war crimes, for goodness sake, must be a course that can bring us closer together instead of dividing us further apart," the British prosecutor said.