Meeting in the Russian Black Sea resort of Sochi, representatives of Russia, Iran, and Turkey have kicked off two days of talks on issues related to the war in Syria.

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.

In comments published by Turkish media on July 29, President Recep Tayyip Erdogan said the meeting would take place in Istanbul on September 7.

The Turkish leader gave no details about the issues on the agenda, but he said Turkey would continue dialogue with Russia, "outside of this foursome," according to the Hurriyet daily.

There was no immediate confirmation from Russia, France, or Germany.

Russia and Iran have given Assad crucial support throughout the war in Syria, which has killed hundreds of thousands of people and uprooted millions since it began with a government crackdown on protesters in March 2011.

Russia helped turn the of the conflict in Assad's favor when it launched a campaign of air strikes on his opponents and stepped up its military presence on the ground in Syria in 2015.

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

With reporting by AFP, dpa, TASS, and Interfax