Finnish authorities are investigating an oil tanker that is part of Russia’s shadow fleet over whether it cut an electricity cable between Finland and Estonia.

The Eagle S was stopped by Finnish authorities after the Estlink 2 subsea electricity cable in the Gulf of Finland was disconnected on Wednesday. The tanker, which is registered in the Cook Islands and is carrying oil from Russia to Egypt according to ship tracking data, was seen passing over the cable at the time of the incident.

The aged tanker is part of Russia’s shadow fleet and is the focus of Finland’s investigation, according to people familiar with the probe. The Eagle S is also under investigation over whether it cut three communications cables in the Gulf of Finland, the people added.