As the political wranglings continue about the oil spill in San Francisco bay, a greater ecological catastrophe is unfolding between Russia and Ukraine.

A tanker carrying 4,000 tonnes of oil broke up yesterday in heavy seas off the Crimean peninsula, splitting in half. One senior official has called it an “environmental disaster”.

The oil tanker, the Volganeft-139, which had been loaded with about 4,000 tonnes (1.3m gallons) of fuel oil, was stranded about three miles from the shore in the narrow Kerch strait south of the Sea of Azov, in one of the worst ecological disasters in the region for years.

Stormy weather was preventing emergency workers from collecting the spilled oil. At least 1,300 tonnes, and probably more, had leaked into the sea, officials said. “There is serious concern that the spill will continue,” Oleg Mitvol, head of the state environmental safety watchdog Rosprorodnadzor told Russia’s Vesti 24 TV.

“The wind is now blowing in the direction of Ukraine’s coast, so it is our common problem. This problem may take a few years to solve. This is a very serious environmental disaster.”