ASTRAKHAN, September 29. /ITAR-TASS/. President Putin has arrived in Astrakhan to attend the fourth summit of Caspian states which opens on Monday. The heads of the five Caspian states - Russia, Iran, Kazakhstan, Azerbaijan and Turkmenistan, are attending the summit.

First, the leaders of the five Caspian states will meet in a narrow format "to discuss the most sensitive problems on the agenda: the legal status of the Caspian Sea and a military component of the aspect of security," Putin's aide Yuri Ushakov told journalists.

Then the talks will continue in an extended format to be followed by a signing ceremony of joint documents and a statement for the press, Ushakov said. In an informal part of the summit the leaders of the five states will take a stroll on the embankment of the Volga river and will watch a symbolic release of young sturgeon fish into the river.

On Monday evening President Putin will have separate talks with President of Iran Hassan Rouhani, Turkmen President Gurbanguly Berdimuhamedov and President of Azerbaijan Ilkham Aliyev.

President Putin will meet his Kazakh counterpart Nursultan Nazarbayev in a bilateral format in the city of Atyrau in Kazakhstan on September 30 in the framework of an inter-regional forum of the two countries.

The Caspian Sea status issue

The Russian leadership hopes that the Caspian summit will help make headway in a long process of negotiations on the status and delimitation of water areas of the Caspian Sea. A joint political statement to be made by the presidents of the five Caspian states will be a cornerstone of the future Convention on the legal status of the Caspian Sea, Ushakov said.

The Caspian sea is a unique water area in terms of its bio and ecological resource, which includes more than 500 kinds of sea plants and 854 kinds of fish species, including the Caspian sturgeon which accounts for 90% of the world stock of sturgeon fish.

A predicted amount of Caspian hydrocarbon resources has been estimated at around 18 billion tons, with the proved reserves put at four billion tons, which brings the Caspian Sea to second position after the Persian Gulf in the rating of the world biggest oil and gas reserves.