Four participants of the informal summit, including Kazakh President Nursultan Nazarbayev, Russian President Dmitry Medvedev, Azerbaijani President Ilham Aliyev and Turkmen President Gurbanguly Berdymukhamedov arrived in Aktau, akimat told KazTAG correspondent.
"All four presidents have already arrived and gone to the meeting," interlocutor said.
It was earlier reported that the informal summit of heads of the Caspian countries will be held on September 11-13 in Aktau.
Participants of the summit intend to discuss cooperation within integration unions in the post-Soviet sphere, including CIS.
Moreover, the issues in energy and transport spheres of the region are expected to be considered.