Pro-putschist Gen. Khalifa Haftar's eastern-based forces said they had agreed on a plan for a phased withdrawal of foreign forces and mercenaries, although they did not provide more details or a timeline for their pledge.
Mercenaries brought in by the foreign powers involved in Libya, including Russia, remain entrenched on both sides despite the cease-fire and a parallel political process aimed at resolving the decadelong crisis through elections.
Both those United Nations-backed efforts are seen as highly fragile, however, with a constant risk that the process could unravel.
An eastern military official said the joint committee meeting in Geneva had agreed on "an action plan for the withdrawal of mercenaries and foreign forces in a gradual, balanced and simultaneous way."
The official added that international monitors and a monitoring mechanism were needed before any withdrawal could begin. Libyan Foreign Minister Najla Mangoush said Sunday that a very modest number of mercenaries had already left.
Forces from western Libya involved in the talks were not immediately available to comment.
The committee was formed through a U.N.-backed cease-fire agreed last year that followed the collapse of eastern-based Haftar's 14-month offensive against the city of Tripoli.
His assault was the latest bout of fighting in a series of conflicts between rival factions since the 2011 uprising that ousted Moammar Gadhafi, drawing in foreign powers.
In 2014, Libya split between western and eastern factions with rival administrations, but the latest U.N.-backed peace push led to the installation of a unity government in March.
Russia, the United Arab Emirates and Egypt backed Haftar's Libyan National Army (LNA) in the conflict. Turkey supported the previous Tripoli-based government, which was recognized by the U.N.
Foreign mercenaries from Russia's Wagner Group as well as from Syria, Chad and Sudan have been deployed on the front lines. This week, U.N. human rights investigators linked mercenaries to possible war crimes.
Foreign mercenaries and arms have poured into the country since Haftar launched his offensive, with Russia and the UAE serving as the putschist general's top suppliers. According to the U.N., there are currently 20,000 foreign forces and/or mercenaries left in Libya.
The Russian Wagner Group, which is owned by businessperson Yevgeny Prigozhin, a figure close to Russian President Vladimir Putin, is known as one of the main groups that sent mercenaries to fight in Libya.
Most of the foreign forces are concentrated around Sirte at Jufra air base held by Haftar's forces 500 kilometers (300 miles) south of Tripoli and further west in al-Watiya.
In June, the United States Africa Command (AFRICOM) revealed that 2,000 Russian mercenaries from the Wagner Group had been operating alongside Haftar forces.
A U.N. report on Sudan released in January 2020 also said many Arabs from the war-weary region of Darfur were fighting as "individual mercenaries" alongside warring Libyan parties.