The United Nations special envoy for Libya Jan Kubis has resigned weeks ahead of Libya's highly-anticipated presidential election, according to diplomatic sources.

Kubis' resignation comes on the day Libya's election commission announced 98 candidates who will contest in the December 24 election.

A diplomat who spoke to AFP on condition of anonymity said: "Kubis has resigned."

There was no official reason given for Kubis' resignation which comes less than a year after he took up the role in January.

The former Slovak foreign minister succeeded Ghassan Salame, who left the role in March last year due to stress.

Kubis also previously served as the U.N. special coordinator for Lebanon and as the U.N. special envoy in Afghanistan and Iraq.

The development will do little to inspire confidence in the North African nation where there is constant speculation about attempts to disrupt the elections to undermine the democratic transition process in Libya.

(With input from agencies)