Vladimir Putin has said the Syrian government will allow a demilitarised zone around Idlib.
The Russian president said the 15-20km (9.3-12.4 miles) wide safe zone will be created in the northwest Syrian province by 15 October.
He agreed with his Turkish counterpart, Recep Tayyip Erdogan, on the buffer zone during a meeting in Sochi, southern Russia.
Forces from both countries will patrol it, he said.
Mr Putin said the move is supported by the Syrian president, Bashar Assad, whose forces have been strengthening along the province’s borders in recent days to try to recapture it after seven years of civil war.
As part of the zone, Mr Putin said “radically minded” rebels, including the al Nusra front, must withdraw from the area.
All heavy weapons must be withdrawn from the zone by 10 October, he added.