Video appears to show one of the tankers broken in half and sinking amid a heavy storm, with oil visible in the water.

Russia has opened two criminal investigations into potential safety violations after at least one person died and another tanker was significantly damaged in the weather.

Near the Kerch Strait, two Russian oil tankers malfunctioned, and one of them broke in half. "The disaster could become one of the largest man-made catastrophes in the Black Sea," Greenpeace stated in a comment published by the Russian independent portal Meduza.