Finnish police said on Thursday they are investigating whether a foreign ship was involved in the damage of an undersea power cable connecting Finland and Estonia following a sudden outage on Wednesday.

Finland's public transport agency said on Wednesday that an oil tanker suspected of damaging undersea cables in the Baltic Sea was found to have serious deficiencies and will not be allowed to operate until repairs have been made.

Finnish police say authorities detained a ship linked to neighboring Russia as they investigate whether it damaged a Baltic Sea power cable and several data cables.

The anchor of the Eagle S oil tanker has been recovered from the bed of the Baltic Sea during an inquiry into the ship's possible involvement in sabotage of maritime energy and communication cables. The EU says the tanker belongs to the so-called Russian shadow fleet.

Finland's national power grid operator said on Thursday it had asked a Helsinki court to seize the Eagle S oil tanker in a bid to secure the company's claim for damages related to the breakdown of the undersea Estlink 2 electricity interconnector.

Finnish police have reported finding the anchor responsible for severing an undersea internet cable connecting Finland to Estonia. Last month, Finland detained the Eagle S, an oil tanker transporting Russian oil,