The five nations that border the Caspian sea say they’ve reached agreement in principle on how to divide up the oil and gas resources of the world’s largest enclosed body of water.

But at a meeting in Kazakhstan, no deal was found on the more contentious issue of where the seabed border should be traced.

Russia, Iran, Kazakhstan, Turkmenistan and Azerbaijan say the bulk of the waters will be considered as a common resource and that the Caspian will given a special status that is neither that of a sea or a lake. The division of lakes and seas is already governed by international law.

The Caspian is believed to hold some 50 billion barrels of petrol and 300 000 billion cubic metres of natural gas. It is also a favoured route for energy pipelines.

But exploitation of the resources has been hampered by disputes over ownership which date back from the breakup of the Soviet Union.