Fayez al-Sarraj, the embattled head of the unity government in Libya, is due to attend the summit in Congo’s capital Brazzaville, his advisor told AFP on Thursday.
However, strongman Khalifa Haftar, who backs a rival administration in eastern Libya, will not take part despite being invited, his spokesman said.
Instead, Aguila Salah, the head of the elected parliament in the east, will be attending.
It is the latest attempt to put an end to six years of chaos in oil-rich Libya where rival militias and administrations have been vying to control the country’s wealth and cities.
Libya was plunged into turmoil following the overthrow of long-time dictator Moamer Kadhafi in 2011 with dozens of armed factions filling the power vacuum.
Sarraj has struggled to assert his authority across Libya since he took office in Tripoli in March 2016, with Haftar, who also controls much of Libya’s desert south, refusing to recognise the government.
In July, the two rivals committed to a ceasefire and holding elections as soon as possible at talks brokered by French President Emmanuel Macron in Paris.
Saturday’s summit will be the third held by the African Union High Level Committee on Libya, made up of the presidents of Congo-Brazzaville, Ethiopia, Mauritania, Niger and South Africa. It will be chaired by Congolese President Denis Sassou Nguesso.