Russian President Vladimir Putin, one of the Syrian government's closest allies, hosted a summit in the Black Sea resort of Sochi on Thursday to discuss the future of Syria with Turkish President Recep Tayyip Erdogan and their Iranian counterpart Hassan Rouhani.

The leaders met to find a consensus on how to carve up Syrian territory in the wake of the planned withdrawal of American troops.

Russia appeared to warn of a military offensive against Hay'et Tahrir al-Sham if Turkey does not enforce a demilitarised zone in Idlib province.

Turkey has been eager to avoid such an attack because it worries about the creation of a humanitarian crisis on its border.

Zeina Khodr reports from Tehran.