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.

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.

Finnish police said on Tuesday they have recovered a lost anchor from the bottom of the ocean as part of an investigation of suspected sabotage against power and internet cables in the Baltic Sea. Finland last month seized the Eagle S tanker carrying Russian oil on suspicion that the vessel had damaged the Finnish-Estonian Estlink 2 power line and four telecoms cables by dragging its anchor across the seabed.

Finland's Elisa said on Monday that it had finished the repair of its two undersea telecommunications cables that were damaged in the Baltic Sea on Dec. 25. Finland on Dec. 26 seized the Eagle S tanke

The Eagle S, thought to be part of Russia’s “shadow fleet,” was detained in December following suspected sabotage.

Northern European countries, part of the Joint Expeditionary Force, have enhanced the protection of underwater cables in the Baltic Sea. Artificial intelligence is being used to monitor the Russian fleet.