Fierce winds on Tuesday hampered crews struggling to clean up in the wake of a killer storm that sank at least 11 ships and split an oil tanker in two, spilling tonnes of petroleum in the waters between Ukraine and Russia.
Officials called the breakup of the tanker in the Kerch Strait an environmental disaster and warned that the 2,000 tonnes of spilled fuel oil, which has killed 30,000 birds according to some estimates, could cause long-lasting damage to marine life.
Leading Russian environmentalists, meanwhile, said the oil spill was triggered by years of official negligence that allowed oil transport ships to use outdated and inadequate equipment.
"It's a long-expected disaster," environmentalist Sergei Golubchikov told journalists in Moscow. "We could lose the Black Sea if we go on this way."
Russia has a lot riding on the health of the Black Sea. Russian President Vladimir Putin has pledged to spend US$12 billion on developing the port of Sochi as the site of the 2014 Winter Olympics.
The ships sank or ran aground in Sunday's gale, including the tanker that spilled the fuel and a freighter carrying sulfur, officials said. The bodies of three crew members from the freighter have been found, but five crewmen, are still missing, Emergency Situations Ministry spokesman Sergei Kozhemyaka said.
High winds have prevented salvage teams from launching an effort to sweep the oil off the water's surface, officials said, allowing patches of the slick residue to drift to the seabed, where it could linger for years.
Yelena Vavila, an expert with the regional environmental monitoring agency, warned about "increased concentration of oil in the water for at least five years."
The most important task now is to build a dam to prevent the slick from floating into the Sea of Azov, said Oleg Mitvol, deputy head of the Russian state environmental safety watchdog Rosprirodnadzor.
"We have a real chance to save the ecosystem of the Sea of Azov," he said.
However, Russia and Ukraine have a long-running argument over which country controls what parts of the waterway.
Russian Prime Minister Viktor Zubkov said that most of the oil could be cleaned off the shoreline within three weeks.