More than 200 dead seals have been found on Kazakhstan`s coast of the oil-rich Caspian Sea, a local fishery official said on Thursday.

The northern Caspian has been plagued by similar incidents for years, with some environmentalists saying mass seal deaths that began to be reported in the 1970s coincided with the start of an active oil exploration on the Caspian shelf.

"Border guards found 218 dead seals while patrolling the coast on May 12, the carcasses were in a state of decay," Marat Akhmetov said.

Akhmetov said experts had taken soil and sea water samples at the site for testing along with animal tissue samples, and the carcasses had been burnt.

Last April, over 30 dead seals were washed ashore near the Kalamkas oil field in Kazakhstan, and a total of 928 seals, including 710 baby seals, died near the oil field in March 2007.

Kazakh experts then established that the phocine distemper virus (PDV) was responsible for the deaths. But some environmental groups said environmental pollution suppressed the seals` immune systems and made them vulnerable to the disease.

In 2000, chronic intoxication killed 10,500 seals in the region. For several years the animals had been absorbing oil toxins and pesticides, which damaged their immune resistance, experts said.

Prosecutors in the regional center Aktau said on Thursday they had launched a probe into the seal deaths, and would look into poaching as one of the possible causes.

The animals could have died in poachers` nets as some of the carcasses had traces of fishing nets on them, a prosecutor said, adding that examination of the coastline was continuing.
sections: Society