Finland's power grid operator Fingrid 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 Estlink 2 electricity cable.

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.

The owner of an oil tanker seized by Finland on suspicion of breaking an undersea power line and four telecoms cables in the Baltic Sea last week is seeking the release of the ship, a lawyer representing the company said on Monday.

The damaged cable is one of several recent incidents in the Baltic Sea under investigation as possible acts of sabotage.