Libya's top electoral body said on Wednesday that the son and one-time heir apparent of the late Libyan dictator Muammar Gaddafi is disqualified from running in presidential elections that are supposed to take place next month.

According to a list of barred candidates issued by the country's High National Elections Committee, Seif al-Islam Gaddafi is ineligible because of previous convictions against him. He can appeal the committee's decision in court within the coming days.

Seif al-Islam was sentenced to death by a Tripoli court in 2015 for use of violence against protesters who were calling for his father to step down, but that ruling has since been called into question by Libya's rival authorities.

He is also wanted by the International Criminal Court on charges of crimes against humanity related to the 2011 uprising against his father.

Libya is set to hold the first round of its presidential elections on Dec 24, after years of United Nations-led attempts to usher in a more democratic future and bring the country’s war to an end.

Adding to the complexity and concerns surrounding the election, the UN's top envoy for Libya recently decided to quit, though he said on Wednesday that he’s prepared to stay on if needed through the vote.

Following the overthrow and killing of Gaddafi, oil-rich Libya spent most of the last decade split between rival governments — one based in the capital, Tripoli, and the other in the eastern part of the country.

Each side in the civil war has also had the support of mercenaries and foreign forces from Turkey, Russia and Syria and other regional powers.

Also read: Son of former Libyan ruler Gaddafi runs for president

The son of Libya's former dictator submitted his candidacy papers in the southern town of Sabha, 650 kilometres (400 miles) south of the capital of Tripoli on Nov 14. It was the first time the 49-year old, who earned a PhD at the London School of Economics, had appeared in public in years.

He was captured by fighters in the town of Zintan late in 2011, the year when the popular uprising, backed by Nato, toppled his father after more than 40 years in power.

Muammar Gaddafi was killed that same year in October amid the ensuing fighting that would turn into a civil war. The dictator's son was released in June 2017.

The announcement of his possible candidacy has stirred controversy across the divided country, where a number of other high-profile candidates have also emerged in recent weeks.

Earlier this month, several controversial candidates came forward, including powerful military commander Khalifa Hifter, and the country's interim prime minister, Abdul Hamid Dbeibah.

The long-awaited vote still faces challenges, including unresolved issues over laws governing the elections, and occasional infighting among armed groups.

Other obstacles include the deep rift that remains between the country’s east and west, split for years by the war, and the presence of thousands of foreign fighters and troops.

Meanwhile, UN envoy Jan Kubis submitted his resignation last week, though it didn't become public until Tuesday.

The Geneva-based diplomat serves as both a special envoy for Libya and head of the UN political mission in the country.

He told the Security Council on Wednesday he's leaving to facilitate a change he considers vital: moving the mission chief's job to Tripoli to be on the ground at a high-stakes moment for Libya.

The idea divided the council during discussions in September. Western countries embraced it; Russia rejected it.

Kubis added that he was ready to continue as a special envoy through the December 24 election, though he said the UN had accepted his resignation with a 10 December effective date.

Asked about the discrepancy, UN spokesperson Farhan Haq said the organisation would "continue to work with him while we’re seeking a successor.”

The job was open for nearly a year before being filled by Kubis, a former Slovak foreign minister and UN official in Iraq and Afghanistan.

The Security Council emphasised the importance of the upcoming election in a statement on Wednesday, urging an “inclusive and consultative electoral process,” warning against violence and disinformation and calling for Libyans to accept the results of the vote.

Libyan Ambassador Taher El Sonni said his country appreciates “all international initiatives with genuine intentions,” but he said the council’s members need “to heed us, too” and let Libyans lead their own way out of crisis.

“You have a moral responsibility towards the developments in my country over the past 10 years,” he told the group. “Don’t belittle us.”