MOSCOW, Russia (CNN) -- Residue from a large oil spill in the Black Sea region will take more than a month and a half to completely clear, Russian officials said Thursday.
The Ministry for Emergency Situations. ministry said improved weather was helping the effort to clear the spill, which environmentalists fear could damage the area for years.
About 2,000 workers are being called on to clean up the oil which has washed up over the past few days.
The oil has been mixed with seaweed, dead fish, and dead birds.
The ministry predicted it would take another seven to 10 days to skim the remaining oil off the surface of the sea, and another 45 days to clean up what remains.
As of Wednesday, the ministry said, more than 1,500 tons of oil products and polluted seaweed had been collected along the shore.
The oil spilled Sunday when a tanker traveling through the Kerch Strait at the northern end of the Black Sea went down in a storm, spilling more than 1,000 tons of fuel oil.
The strait divides Russia and Ukraine's Crimean Peninsula and connects the Black Sea and the Azov Sea to the north.
Half of the oil remained in the strait but some was spreading north and could reach the Azov Sea in a day, Russia's Hydrometeorology and Environment Monitoring Service said Thursday, in a report by Interfax news agency.
The governor of Russia's Krasnodar region, which borders the Black Sea and the Kerch Strait where the oil spill happened, said Wednesday an estimated 30,000 birds had died and the same number were covered in fuel oil, Russian media reported. He said it was impossible to say how many fish had died.
"The damage is so great that it is very hard to estimate," governor Alexander Tkachev said. He called the situation an "ecological disaster."
Sunday's storms produced hurricane-force winds and massive waves which caused a total of five ships to sink -- four in the Kerch Strait and one on the other side of Crimea -- and many more to run aground.
The emergency ministry has said three sailors died and 20 others remain missing. The official Russia Today Web site reported five dead, but it did not name a source for its information.
While the weather had improved by Thursday, strong winds remained. CNN Forecaster Jenny Harrison said an approaching storm system to the west of the Black Sea would bring an increase of rain and wind over the next few days.
Environmentalists have said the spill was partly the result of lax Russian restrictions on the transportation of oil. They say many vessels are old and poorly maintained or -- like the freighter which sank, the Volganeft-139 -- are meant for use on rivers, not the sea. E-mail to a friend
CNN's Matthew Chance in Kavkaz and Max Tkachenko in Moscow contributed to this report.
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