Finland has seized an oil tanker suspected of having severed undersea power and internet cables, with Finnish authorities saying the vessel may have been part of Russia's "shadow fleet" of ships aimed at skirting Western sanctions.

The Finnish customs service said the ship may belong to the shadow fleet of aging tankers that seek to evade sanctions on the sale of Russian oil.

The Eagle S – a tanker ship carrying Russian oil and suspected of severing the Estlink 2 power cable running under the Baltic Sea between Finland and Estonia – was reportedly brimming with spy equipment.