At least 63 kilometers of coastline in Russia's southern region of Kuban has been covered by heavy fuel oil from two oil tankers that ran aground in the ecologically sensitive waters off Ukraine's Moscow-annexed Crimean Black Sea coast.
The Emergency Situations Ministry reported on December 31 that while almost 70,000 tons of contaminated sand and soil were collected from the coast, new pockets of fuel oil have been found.
The accident, which occurred on December 15, left one sailor dead and forced the evacuation of 26 crew members from the vessels Volgoneft-239 and Volgoneft-212.
Officials have said crew error during stormy conditions was to blame and there was no evidence of any links to Russia's war on Ukraine.
Both tankers were laden with large cargoes of fuel oil. The Volgoneft-212 is said to have been carrying more than 4,000 tons of the heavy pollutant, leaving the potential for one of the largest environmental disasters ever in the Kerch Strait, which is a key shipping lane.
Volunteers have been racing to clean up the spill but have complained that instead of receiving special equipment from the government, people were being forced to clean up the fuel oil with shovels and scoops while breathing in toxic fumes.
They said the situation is so bad that they appealed to President Vladimir Putin to intervene and send additional forces to clean up the shore and save marine wildlife.
"After 2 1/2 hours, even if you're wearing a respirator mask, goggles, gloves, and are fully protected, the fumes start to take a toll. You feel a headache, nausea, and start vomiting," Ksenia Vysotskaya, one of the volunteers working to clean up the Russian coast, told RFE/RL.
"I had to lie down for several hours afterward."
The vessels were were about 7 kilometers from the shore in the Kerch Strait between mainland Russia and Crimea, which Russia illegally annexed from Ukraine in 2014, when they issued distress signals.
In 2007, the strait, which links the Sea of Azov to the Black Sea, saw the Volgoneft-139 tanker split in half during a storm while anchored nearby, spilling more than 1,000 tons of oil.
Greenpeace called on the Russian authorities "to take all efforts to mitigate or reduce environmental impact of the oil spill, and withdraw the navy ships, and stop militarization of the region, returning Crimea under rightful control of Ukraine."
Experts have warned the environmental impact of the accident "is very likely to be astronomical," with the potential cost of cleanup seen at more than $100 million.
Russia uses "shadow tankers" -- vessels that are not Western-owned or Western-insured, to skirt sanctions that prohibit it from selling oil and oil products at rates that exceed a set price cap, which varies for crude and different kinds of oil products.
Andriy Klymenko, project director at the Kyiv-based Institute of Strategic Black Sea Studies, wrote on Facebook that the vessels are "not seagoing vessels" but are river vessels that are permitted to travel in coastal waters.
According to Klymenko, neither of the tankers was authorized to sail in seas where waves are higher than 2.5 meters, while he said the waves in the Kerch Strait were reaching 3.5 meters on December 15.