Turkish President Recep Tayyip Erdogan held talks with Libyan Prime Minister Fayez al-Sarraj in Istanbul on Thursday, after Turkey said its commitments in Libya were connected with a ceasefire.
Turkey supports the UN-recognised Government of National Accord led by Sarraj, and the two countries signed security, military and maritime deals in November last year.
The closed-door meeting had not been on Erdogan's official agenda and took place at the Ottoman-era Dolmabahce Palace, the Turkish presidency said, without giving details.
Earlier on Thursday, Libya's warring sides resumed talks in Geneva aimed at brokering a lasting ceasefire in the country.
Libya has been mired in chaos since 2011 when a NATO-backed uprising led to the killing of longtime dictator Moamer Kadhafi.
Military strongman Khalifa Haftar, backed by the United Arab Emirates and Saudi Arabia, launched an offensive on Tripoli last April.
A ceasefire brokered by Haftar-supporter Russia and GNA-backer Turkey was agreed last month by both sides to end fighting but there have been violations.
Turkish Foreign Minister Mevlut Cavusoglu earlier on Thursday told state broadcaster TRT Haber that Turkey's commitments in Libya were "connected to the ceasefire".
At a Berlin summit last month, countries including Russia, Turkey, France and Egypt agreed to end foreign interference in Libya and respect for a UN arms embargo.
"If the ceasefire does not continue, the transfer to a political process is very hard," Cavusoglu said. "The world condemns but what is being done to stop Haftar?"
Libya's unity government halted its participation in UN talks this week after a barrage of rocket fire hit a port in the capital Tripoli, but returned to the table on Thursday.