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

Finnish authorities on Thursday seized a ship carrying Russian oil in the Baltic Sea on suspicion it caused the outage of an undersea power cable connecting Finland and Estonia a day earlier, and that it also damaged or broke four internet lines.

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.