Spilled oil has washed up along "tens of kilometers" of the Russian Black Sea coast after two tankers were badly damaged in a storm at the weekend, a local governor said on Tuesday.
Veniamin Kondratyev, the governor of Russia's southern Krasnodar region, said on his Telegram channel that fuel oil had been found along the coast from the districts of Temryuk to Anapa.
"This morning, while monitoring the shoreline, stains of fuel oil were discovered. Oil products washed ashore for several tens of kilometers," he said.
The Volgoneft 212 tanker split in half on Sunday in the Kerch Strait, between the Black Sea and the Sea of Azov, while the Volgoneft 239 ran aground 80 meters (87 yards) from the shore near the port of Taman in the strait.
The more than 50-year-old ships were carrying some 9,200 metric tons (62,000 barrels) of oil products in total, Russian news agency TASS reported, raising fears it could become one of the largest environmental disasters to hit the region in years.
A video posted on Zvezda TV's Telegram channel on Tuesday showed a black, oil-like substance along the coast of the Black Sea resort of Anapa, southeast of the Kerch Strait.
The video showed oil-like stains along a beach strewn with tree branches.
Meanwhile, a video broadcast by the state TV channel Vesti showed several birds covered with oil flapping their wings and struggling to fly.
Russia's Natural Resources and Ecology Ministry said on Monday that fuel oil had leaked into the sea, but the scale of the spillage was still not clear.
Natural Resources and Ecology Minister Alexander Kozlov said some of the fuel oil could have sunk to the seabed due to cold weather.
The shipping industry has raised concern in recent months over the risks and potential for collisions posed by hundreds of "shadow" tankers in open sea lanes, with little incentive for these vessels to follow cleaner shipping standards.
The Kerch Strait, which separates mainland Russia from the Moscow-annexed Crimea region, is a key route for exports of its grain and fuel products.
One member of the Volgoneft 212's crew was killed in Sunday's accident, while all 14 people on the Volgoneft 239 were rescued.