The leaders of the two main sides of Libya's civil war are in Moscow for talks on how to end months of fighting.
It is hoped both the UN-backed government and forces loyal to Russian ally Gen Khalifar Haftar will sign a ceasefire.
The talks are part of an initiative launched by Russia and Turkey at a summit in Istanbul last week.
A first tentative truce started on Sunday but both sides accused each other of breaking it within hours.
On Monday, Russian and Turkish officials will first hold talks separately with the two warring sides, and a meeting of all four groups is expected to follow.
The meeting underlines how Turkey and Russia are emerging as the critical players in the complex web of competing foreign interests in Libya, the BBC's Moscow correspondent Sarah Rainsford says.
Over the weekend, German Chancellor Angela Merkel said Berlin later in January wanted to host another round of Libyan peace talks to build on the efforts by Turkey and Russia.
Russia has been backing General Haftar, who is trying to capture the capital Tripoli, while Turkey supports the internationally recognised government there.
Turkey last week sent troops to help Government of National Accord forces.
Gen Haftar is also backed by Egypt, Saudi Arabia, the United Arab Emirates (UAE), and Jordan, raising fears that oil-rich Libya could become the theatre of a regional conflict, or even a "second Syria".
Amid the chaos, both Islamist militant groups and migrant smugglers have become well-established, causing particular concern in European countries just across the Mediterranean Sea.
Libya has been wracked by conflict since the 2011 uprising which ousted long-time strongman Muammar Gaddafi.
The Libyan National Army (LNA) forces loyal to Gen Haftar control most of eastern Libya. They launched an offensive on the capital in April 2019 but have been unable to take the city.