Russian President Vladimir Putin is hosting the leaders of Turkey and Iran for talks about a Syria peace settlement as expectations mount for an imminent and final defeat of the Islamic State group.

The talks are expected to kick off in the Black Sea resort of Sochi on Thursday.

Russia, a key backer of Syrian President Bashar Assad, is getting increasingly impatient about militants in Syria's Idlib province.

Russia and Turkey, which supports the Syrian opposition, had brokered a cease-fire for Idlib, the last remaining rebel stronghold that averted a major government offensive but that deal has been strained as al-Qaida-linked militants seized towns and villages in Idlib.

Kremlin spokesman Dmitry Peskov says Russia is going to raise its concerns at the talks about the presence of "terrorists" there.