The first document on the Caspian Sea environment protection is to be inked in Tehran on Tuesday by the representatives of the littoral states, IRNA reported.

Director General of the Maritime Affairs of the Department of Environment Mohammad Saeed Hosseini in an interview with IRNA said the document would set an official framework for the establishment and promotion of the cooperation among the Caspian sea littoral states to deal with the environmental issues.

The measure would be a turning point as for the environment protection cooperation among the regional states on the Caspian, he noted.

Eight preliminary sessions had been previously held to forge a consensus among the relevant states on the clauses of the document, he added.

The official reiterated that ministers of environment of all the Caspian sea littoral states would gather in Tehran next Tuesday to ink the first document on the Caspian Sea environment protection.

On Monday, experts from the five states surrounding the Caspian Sea would hold expert talks to remove any ambiguities on the watershed document prior to its final signature, he explained.

The official said the United Nations Environment Program (UNEP) would supervise the signing procedures.

Ministers from Azerbaijan, Iran, Kazakhstan, the Russian Federation, and Turkmenistan have already given their support for the document.

The ground-breaking agreement, the first legally binding treaty on any subject to be adopted by the five neighbors, will coordinate regional efforts to reverse an environmental crisis brought about by habitat destruction, pollution and the over-exploitation of fish and other marine life.

It is expected to promote the conservation of the largest freshwater lake in the world, said Saeed Hosseini adding that the Caspian Sea is now under severe stress from industrial pollution, toxic and radioactive wastes, agricultural run-off, sewage, and leaks from oil extraction and refining.

Threats posed to the Caspian Sea include uncontrolled fishing of caviar-producing sturgeon, the over-exploitation of other marine resources, and the destruction of the region's biological diversity, which includes some 400 species unique to the Caspian.

With an area of some 373,000 sq km, the Caspian Sea boasts a shoreline of 7,000 km in length. Its surface is 28 m below sea level, and its maximum depth is 980 m. The lake is fed by some 130 tributary rivers, although 75 per cent of its inflow comes from just one - the Volga River.

The Caspian Sea is also unique in that its waters hide some of the largest oil reserves in the world.