The decision follows a spate of suspected sabotage incidents on underwater cables.

The Finnish operator of the cables suspected to have been damaged by a vessel from Russia's shadow fleet on Christmas Day says the cables have now been repaired. A power cable damaged that day is still out of service.

General Mark Rutte says the military alliance will step up patrols in the Baltic Sea area as Finnish investigators work to establish whether a ship linked to Russia sabotaged undersea cables there this week.

Two undersea telecommunications cables that were damaged in the Baltic Sea on Dec. 25 appeared to have been torn apart by a strong external force, Finland's Elisa said on Monday, adding that they had now been repaired.

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 tanker carrying Russian oil on suspicion that it damaged the Finnish-Estonian Estlink 2 power line and four telecoms cables on Christmas Day by dragging its anchor across the seabed.

Finnish authorities have found and retrieved the anchor of the Eagle S tanker, suspected of damaging cables in the Baltic Sea. Investigators will begin inspecting it on Tuesday. Finnish radio Yle reported that the tanker Eagle S's anchor was located at the bottom of the Gulf of Finland and brought to the surface.