Iranian Foreign Minister Mohammad Javad Zarif has met with Russian President Vladimir Putin during a visit to Russia’s Black Sea resort town of Sochi on September 13.
The Kremlin press service confirmed the meeting but did not release details of the discussions.
Earlier, Russian Deputy Foreign Minister Mikhail Bogdanov said Zarif's talks with the Russian leadership would focus on the conflict in Syria as well as "the Middle East in general, issues related to Iran's nuclear program, and the situation in Iraq and the Persian Gulf region."
The meeting comes a day before the start of a sixth round of Syria peace talks in Astana that are sponsored by Russia, Iran, and Turkey -- negotiations that are separate from United Nations-sponsored talks in Geneva.
Experts from Russia, Turkey, and Iran arrived in Astana ahead of the two-day talks and were holding consultations there on September 13.
Syria's UN ambassador, Bashar al-Jaafari, and a Syrian government delegation also arrived in Kazakhstan's capital on September 13 for the Astana talks, which will include representatives of some Syrian opposition groups and an observer mission from the United States.
The U.S. delegation is headed by David Satterfield, the U.S. acting assistant secretary of state for Near Eastern affairs.
The U.S. State Department said Satterfield would "reinforce U.S. support for all efforts to achieve a sustainable de-escalation of violence and provision of unhindered humanitarian aid."
But it said Washington "remains concerned with Iran's involvement as a so-called 'guarantor' of the Astana process."
It says Iran's "activities in Syria and unquestioning support" for Syrian President Bashar al-Assad's government "have perpetuated the conflict and increased the suffering of ordinary Syrians."
According to Kazakhstan's Foreign Ministry, the meeting is expected to focus on how to regulate the operations of "de-escalation forces in Syria and formation of the control forces in Idlib," a Syrian province bordering Turkey.
Russian Foreign Minister Sergei Lavrov said on September 10 that Moscow hoped agreements on a fourth de-escalation zone in Syria near the city of Idlib will be formalized at the meeting.
Russia media reports have quoted senior Russian military officials as saying that Moscow wants Russian military police units to be deployed in Idlib to monitor a cease-fire.