"I am quite confident we are close to a consensus,"Ghassan Salame told the UN Security Council which met to discuss the crisis in Libya.
The United Nations in September launched a new plan to bring stability to Libya which has been in chaos since the 2011 ouster of long-time dictator Moamer Kadhafi.
Two meetings have since been held in Tunis to agree on changes to a 2015 political deal that set up a Government of National Accord led by Prime Minister Fayez al-Sarraj.
Despite that agreement, Libya remains divided between the UN-backed government in Tripoli and a rival administration in the east that enjoys support from Egypt, Russia and the United Arab Emirates.
One of the main stumbling blocks is the inclusion in the new government of Khalifa Haftar, the powerful leader whose Libyan National Army dominates the country's east.
Since the meetings in Tunis, the rival bodies have been in constant contact, said Salame.
"Though much progress was made, a few remaining points are still to be agreed," he added.
Once a deal is struck on a unity government, a national conference will be held in February 2018 to adopt a new constitution that would pave the way for elections.
A mass of migrants have made the lawless country their launchpad into Europe, and the United States has carried out air strikes against Islamic State group jihadists in the North African state.
Salame raised concerns about increasing numbers of migrants and refugees detained in Libya with no due process and subjected to torture, rape, forced labor and other serious abuses.
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