The Russian Foreign Ministry said that the officials would discuss matters including the formation of a Syrian constitutional committee, the de-escalation zones established in Syria, and humanitarian issues at the July 30-31 talks.

While backing separate sides in the Syrian conflict, Turkey, Russia, and Iran launched a negotiations process last year in the Kazakh capital, Astana, mainly dealing with battlefield issues, such as cease-fires and de-escalation zones.

A separate UN-led round of talks addressing political issues has taken place in Geneva.

The Russian delegation in Sochi is headed by the Kremlin's special envoy for Syria, Aleksandr Lavrentyev. Iranian Deputy Foreign Minister Hossein Ansari and his Turkish counterpart, Sedat Onal, were also expected to attend, along with the UN special envoy for Syria, Staffan de Mistura, and representatives of Syrian President Bashar al-Assad’s government.

The gathering comes as Turkey announced on July 29 that it is planning to hold a summit with France, Germany, and Russia in early September to discuss the Syrian conflict and other regional issues.

Turkey backs rebel groups fighting President Assad’s government, while the United States, France, and Germany also back rebel groups, although not always the same groups as Turkey.