Such a meeting would mark the highest-level talks between Ankara and Damascus since the Syrian war began in 2011 and signal a further thaw in ties.
The official, who was not authorized to speak publicly, said the meeting could happen either before or after Turkish Foreign Minister Mevlut Cavusoglu is scheduled to meet US Secretary of State Antony Blinken in the United States on Jan. 18.
"Discussions are continuing (and) an exact date is not yet set. There are no problems with the meeting, they are just working on timing," the official said, adding it would happen either in Moscow or another location, according to Reuters.
The Turkish and Syrian defense ministers held landmark talks in Moscow last month to discuss border security and other issues. Last week, Turkish President Tayyip Erdogan said he may meet Assad after a trilateral foreign ministers meeting.
Syrian newspaper Al-Watan reported on Monday there were no specific dates set for the trilateral meeting. Moscow has not commented on meeting plans.
MP/PR