Rouhani headed to the Russian city of Astrakhan on Sunday to participate in the summit slated on Monday after he wrapped up his visit to New York where he attended the 69th annual session of the United Nations General Assembly.
Iran, Russia, Kazakhstan, the Republic of Azerbaijan and Turkmenistan are the five littoral states of the Caspian Sea.
The last meeting of the Caspian Sea littoral states was held in the Azeri capital city of Baku in November 2010.
The Caspian Sea is the largest enclosed body of water by area, and is variously classed as the world's largest lake or a full-fledged sea.
The issue of the Caspian Sea’s legal regime has gained importance following the breakup of the Union of Soviet Socialist Republics (USSR) and the emergence of newly independent states.
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