The inland, oil- and gas-rich sea has been a source of long-running disagreements between the five littoral states - Azerbaijan, Iran, Kazakhstan, Russia and Turkmenistan - since the collapse of the Soviet Union in 1991.
The countries have failed to agree on how to divide the seabed. The Caspian's oil and gas reserves, believed to be the world's third largest, have also been a source of rivalry between Russia, Iran and the West.
"The sides are interested in intensifying the process of determining the sea's status," Mehti Safari told reporters after a session of the working group on the Caspian.
At a summit in Tehran in October 2007, Caspian leaders failed to make any headway in resolving the dispute, but adopted a joint political declaration promoting efforts to build and enhance mutual confidence, regional security, and stability, and to refrain from the use of force in solving mutual problems.