ANKARA, Feb. 8 (Xinhua) -- Turkish President Recep Tayyip Erdogan and his Russian counterpart Vladimir Putin agreed by phone early Thursday to hold next Syria summit between Turkey, Russia, Iran in Istanbul.

During the phone conversation, two leaders discussed the Syrian crisis, including the latest developments in Idlib and Afrin regions, and exchanged views on the Astana process, presidential sources said citing by state-run Anadolu Agency.

Turkish and Russian presidents agreed to speed up the establishment of new observation points in the de-escalation zones in Idlib.

Erdogan also briefed Putin on the ongoing Operation Olive Branch in the northwestern Syrian region of Afrin which was launched by Turkish army on Jan. 20

The last Syria summit attended by Turkish, Russian and Iranian presidents was held in the Russian Black Sea city of Sochi on Nov. 22.