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 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.

Damage to the power cable in the Baltic Sea is the latest in a spate of murky disruptions to undersea cables that have put European authorities on high alert.