In July, Turkish President Recep Tayyip Erdogan announced the summit of leaders of the four countries that will be held in Istanbul on September 7.
Erdogan said that the leaders would discuss the Syrian conflict as well as other issues. Kremlin spokesman Dmitry Peskov told reporters that the meeting had not been on the agenda yet.
The aide also said that Russian President Vladimir Putin and German Chancellor Angela Merkel had discussed the four-lateral format of talks during their Saturday meeting.
On Sunday, Peskov also told reporters that the new format of the Syrian talks was on the agenda of the negotiations between Putin and Merkel. He pointed out that the expert discussions of the issue would be launched.