The Kremlin has confirmed that Russian President Vladimir Putin, Iranian President Hassan Rohani, and Turkish President Tayyip Erdogan will meet for talks during April.
A March 7 Kremlin statement about the gathering did not specify the exact date or where the meeting would take place.
Russia, Turkey, and Iran are all deeply involved in the war in Syria.
Turkey's Foreign Ministry on March 6 also said that the three leaders would meet in April, but ministry spokesman Hami Aksoy did not say where the summit will be held.
Turkish and U.S. officials are due to meet on March 8 and 9 in Washington.
Aksoy said Turkey would tell U.S. officials that Ankara expects Washington to take concrete steps on retrieving weapons that the United States has provided to Syrian Kurdish YPG militia.
Aksoy also said Turkish Foreign Minister Mevlut Cavusoglu will visit Moscow from March 12 to March14, and then visit Washington on March 19.
He said Cavusoglu plans to meet with U.S. Secretary of State Rex Tillerson during his visit to the United States.