Finnish police are investigating whether a Russian ship was involved in the sabotage of a power cable between Finland and Estonia.

Authorities said Thursday that they believe the anchor of the Eagle S, a Cook Islands-registered tanker, may have damaged the Estlink-2 cable, which was severed Wednesday.

The ship is believed to be part of Russia’s “shadow fleet,” which consists of ships carrying embargoed Russian oil products.

It is the latest in a series of incidents in recent years in which underwater cables in the Baltic Sea region have either been damaged or completely severed.

Fingrid, the operator of Finland’s power grid, said Estlink 2 remained out of service but the damage did not “endanger the operation of the electricity system” in the country.

The repairs are expected to take “several months.”

“From our side, we are investigating serious sabotage,” said Robin Lardot, director of Finland’s National Bureau of Investigation (NBI).

President Alexander Stubb published on X that he had received an “overview” of the cable break from the authorities.

He stressed the need to “address the risks” posed by ships that are part of the Shadow Fleet.

Finnish police said the case was being investigated for “serious criminal mischief.”

The damaged cable had a transmission capacity of 650 megawatts and is 170 km (105 miles) long, of which 145 km is underwater. The fault was located in the submarine section on Thursday.

The EU has threatened to impose further sanctions on Russia over the incident and said it was “stepping up efforts to protect submarine cables”.

“We strongly condemn any deliberate destruction of Europe’s critical infrastructure,” the European Commission and EU foreign policy chief Kaja Kallas said in a joint statement.

Estonian Foreign Minister Margus Tsahkna said on Thursday that damage to critical submarine infrastructure had become “so frequent” that it raised doubts that such damage could be viewed as “accidental” or “merely poor seamanship.”

“We must understand that damage to submarine infrastructure has become more systematic and therefore must be viewed as attacks on our vital structures,” Tsahkna said in a press release.

The Foreign Ministry added that Eagle S was escorted to a Finnish port.

“In addition to evading sanctions, the Shadow Fleet poses a security threat in the Baltic Sea and we cannot simply stand by,” Tsahkna continued.

A telecommunications cable between Finland and Germany was cut in November, and around the same time an internet connection between Lithuania and the Swedish island of Gotland stopped working.

German prosecutors are still investigating the 2022 explosion of the Nord Stream gas pipelines between Russia and Germany.

And in October 2023, a natural gas pipeline between Finland and Estonia was severely damaged.

Finnish officials later said the incident was caused by the towing of a Chinese container ship.