Russian President Vladimir Putin has already held bilateral talks in St. Petersburg with a number of CIS leaders, including the Tajik, Georgian, and Uzbek presidents.
Armenian President Robert Kocharian and Azerbaijani President Ilham Aliyev are also due to continue talks on Nagorno-Karabakh on the summit's sidelines today. Those talks began on June 9.
Representatives of the OSCE's Minsk Group are also expected to take part.
The CIS summit is taking place in St. Petersburg at the same time as an international economic forum. More than 6,000 politicians and business managers from around the world are attending that plenary meeting.
Some 3,000 Russian opposition protesters marched through St. Petersburg on June 9, timed to coincide with the economic forum.
The protest was the latest in a series of so-called Marches of Dissent organized by Other Russia, a loose opposition coalition that accuses President Vladimir Putin of crushing democracy.
Police have forcefully dispersed previous such marches in different Russian cities, but the June 9 rally ended without violence.
(ITAR-TASS, Interfax, AFP)