A storm in the strait between the Black and Azov seas sank four ships, and six ran aground damaging two oil tankers on November 11, causing a spill of around 2,000 metric tons of fuel oil and death.
"The damage is now estimated at 20 billion rubles," said Vladimir Kirillov, head of Rosprirodnadzor.
Kirillov said, however, that the maximum insurance payout will only reach 115 million rubles ($5 million). In November, the environmental watchdog estimated the damage at 6.5 billion rubles ($280 million).
Experts said petrochemical concentrations in the Kerch Strait following the storm were 50 times higher than maximum permissible levels. Some 50,000 birds have so far died as a result of the oil slick. The fuel penetrates birds' plumage causing hypothermia, and is ingested, usually with fatal results.
Ukrainian officials said they planned to charge Russian ship-owners over $1 billion for the damage caused by the spill. Russian and Ukrainian officials are scheduled to meet at the site later this month for talks.
