Heavy fuel oil from Russian tankers is heading towards another Ukrainian city: here's what we know (photos).

Witnesses report that they have observed the movement of heavy fuel oil towards the Ukrainian city of Mariupol, which is currently under Russian occupation. Earlier, a large concentrated oil product spill was detected in the Sea of Azov, but the Russians managed to remove it. However, heavy fuel oil was soon spotted again—this time moving directly towards the city. This information was disclosed on February 3 via a message from the Mariupol City Council on their Telegram channel.

"15 kilometers of the coastal area of the Sea of Azov are contaminated with heavy fuel oil," the message states.

Significant accumulations of oil products had been previously noted in the Sea of Azov: the Russians, who have occupied the Ukrainian coastline, assured the residents of Mariupol and other cities that they had cleaned up the area. The contamination reached an area of 300 square kilometers. The Russians claimed they had managed to remove almost 18 tons of oil products, according to the city council. However, it appears that the threat of pollution to the coastal areas of Mariupol has not diminished.

"Heavy fuel oil has been spotted again. In particular, it is moving towards Mariupol," the Telegram channel reports.

At the same time, the Russians are telling residents of the occupied territories that they have been cleaning up the aftermath of tanker accidents in the Kerch Strait since mid-January, as noted in the report.

It was soon revealed that the summer season in Odessa might be at risk. Specifically, researchers found remnants of oil products in the territory of the "Tuzlovsky Limans" national park. An ecologist stated that it might take 10-15-20 years for the sea to cleanse itself. This information came to light on February 2.