A 22-year-old product tanker sanctioned by the European Union is making an unusual late-season voyage along Russia's Northern Sea Route, highlighting the growing use of older, lower-specification vessels to move petroleum products through the Arctic.

The number of shadow-fleet vessels carrying Russian oil and LNG through the Northern Sea Route has surged this summer, according to a new analysis by the Bellona Environmental Transparency Center, raising concerns about the ability to respond to accidents in one of the world's most remote shipping environments.