The planned meeting is seen as another step towards finding a political solution to end the six-year conflict in Syria.
Rebel groups agreed to attend Syria peace talks backed by Turkey and Russia in Kazakhstan's capital Astana, Syrian opposition negotiators announced on Monday.
Rebel groups took the decision at meetings that are underway in Turkey's capital, Ankara. They are now working to form a delegation that will be different to one sent to peace talks in Geneva last year by a Saudi-backed opposition group.
The Astana talks are scheduled to start on January 23. They are expected to complement the political negotiations in Geneva on the future of Syria and the six-year conflict.
TRT World's Shamim Chowdhury reports from the Turkish city of Gaziantep near the Syrian border.
Turkish military operations in Syria
Turkey's military on Monday said it "neutralised" 18 Daesh members in northern Syria in the previous 24 hours as part of its ongoing Operation Euphrates Shield to protect its borders from terrorist elements.
Turkish authorities often use the word "neutralised" in their statements to indicate the militants in question were either killed or captured.
The army said it hit 180 Daesh targets with tanks and multiple-launch rocket launchers. They included shelters, defence positions, command control centres, and weapons and vehicles.