The rulers of Libya's rival east and west were expected to meet for the first time in more than five months on Monday at a summit in Italy, a week after the United Nations abandoned plans to hold an election next month.
An Italian diplomatic source said Khalifa Haftar, the strongman who rules most of eastern Libya, was on his way to attend the summit.
Haftar had kept the hosts guessing until the final hours whether he would attend.
Libya's prime minister, who is based in the west and has limited authority, had already arrived earlier on Monday.
Italy hopes the conference in the Sicilian city of Palermo will resurrect UN efforts to stage elections in Libya, after the United Nations announced last week that it could not hold a planned election on Dec. 10 because of violence.
The summit will assemble Libya's main rivals for the first time since a similar event in Paris in May, where they had agreed to the plan to hold the December election.
Prime Minister Fayez al-Serraj's western-based government is internationally recognised but has struggled to assert its authority in a country still mostly controlled by armed groups, eight years after NATO-backed rebels toppled long-serving dictator Muammar al-Gaddafi.
A rival government is based in the east, where most towns and cities are under the control of Haftar.
Apart from Haftar, the heads of the two parliaments based in the east and west, Aguila Saleh and Khalid al-Mishri, were also attending, officials said.
Italy, the former colonial power, has vast oil and gas interests in Libya and has been trying to shut down people-smuggling from the Libyan coast.
It has been eager to host a high-profile event, competing with France which staged the May conference.
Apart from Western, UN and Russian officials, Egyptian President Abdel Fattah al-Sisi was also attending.
UN Libya envoy Ghassan Salame told Reuters he hoped another attempt to hold an election will take place by June but Libyans should first hold a national conference in early 2019 to decide on the poll's format.
"We want to ask at the national conference what type of election do you want: parliamentary or presidential, and what kind of law," Salame said.
The envoy said the national conference should "preferably" take place on Libyan soil. Surveys had shown that 80 percent of Libyans want elections to end the stalemate between Libya's rival administrations.
He hoped the Palermo conference would put pressure on the internationally recognised parliament, the House of Representatives (HOR), which has failed to pass an election law.
"The HOR has been sterile, has produced no law ... I think we need wider representation of the Libyans," he said.
France has been courting Haftar, who is supported by Egypt and the United Arab Emirates, which see his forces as a bulwark against Islamists.
Italy is the main backer of Serraj and his weak Government of National Accord (GNA), and has worked with local groups in Libya to stop Europe-bound migrants from embarking by boat.