An animal rescue group said 61 dead cetaceans - an order of aquatic mammals that includes whales and dolphins - had been recorded since the oil spill.

More than 30 dead dolphins have been found in the sea following an oil spill caused by the wreck of two tankers during a storm last month in the Kerch Strait, according to the dolphin rescue center Delpha,

The amount of oil spilled in the Kerch Strait by two Russian oil tankers is "significantly less than the initial estimate," Russia's Transport Ministry claimed on Jan. 2.