Tens of thousands of birds and countless fish have died after thousands of tonnes of oil spilled from a Russian tanker that split in two during a severe storm near the Black Sea, officials said Monday.

"Some 30,000 birds have died and it's not possible to count how many fish. The damages are so great that it's hard to assess. It can be equated with an ecological catastrophe," said Alexander Tkachev, the governor of the Krasnodar region, according to the Interfax news agency.

An oil-covered bird on the shore following the Russian oil tanker spill, which officials are saying could be the worst environmental disaster in the region in years.
(CBC)

Birds weighed down by thick coatings of the fuel oil hopped weakly along the shore or sat helplessly in the sand. Workers with pitchforks and shovels started the backbreaking labour of gathering up vast clumps of oil mixed with sand and seaweed.

The tanker was one of up to 10 ships that sank or ran aground in the storm Sunday in the strait connecting the Black and Azov Seas. The bodies of three sailors from a freighter that also broke apart washed up on shore Monday, and rescuers were looking for five missing crewmen, said Emergency Situations Ministry spokesman Sergei Kozhemyaka.

The spill from the oil tanker was seen as potentially the worst environmental disaster in the region in recent years. It prompted criticism that many Russian tankers aren't seaworthy.

Another regional official, Sergei Zaitsev, was quoted as saying that much of the oil still on the water's surface could congeal in the wintry temperatures, forming globs that drop to the seabed.

Russian President Vladimir Putin ordered Prime Minister Viktor Zubkov to fly to the region to assess the disaster and clean-up efforts.

Three freighters, including the one with the missing sailors, spilled sulphur into the sea when they sank. But Russian officials said the spills did not appear to pose any environmental danger.

Jim Farr, a chemist with the U.S. National Oceanic and Atmospheric Administration, compared the spill to dumping a load of sand in the water and smothering a reef, or covering a patch of grass with a blanket.

However, he said that it was difficult to know the long-term effects without better knowledge of the area's depth and currents.

The Volganeft-139 tanker was carrying about five million litres of fuel oil when the storm sundered it. About half its load has leaked out already, officials estimated. The craft's 13 crew members were rescued.

Expert says tanker intended only for river use

Alexei Knizhnikov, head of the World Wildlife Federation's Russian oil and gas program, said the Volganeft-139 was constructed for river use and was unfit to endure severe weather at sea.

"In the Kerch Strait, river vessels and sea vessels change cargoes, as sea vessels cannot enter the Don and Volga rivers because of small water draft. But vessels constructed for rivers cannot stand strong sea storms," he said.

Anatoly Yanhuck, a regional coast guard officer, said workers would begin pumping oil from the tanker once the weather improves, then tow the ship to port. Investigators would be looking at the actions of the ship's captain, but he said the weather appeared to have been worse than forecast.

Vesti 24 television on Sunday reported the sinking of a Russian freighter carrying metal near the port of Sevastopol on Ukraine's Crimean Peninsula. Two members of its 16-man crew drowned and one was missing, it said.

Maxim Stepanenko, a regional prosecutor, told Vesti 24 that captains had been warned Saturday about the stormy conditions. He said the Volganeft-139, designed during Soviet times to transport oil on rivers, was not built to withstand a fierce storm.