Finnish police said on Sunday they had found tracks that drag on for dozens of kilometres along the bottom of the Baltic Sea where a tanker carrying Russian oil is suspected of breaking a power line and four telecoms cables with its anchor.

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.

Finland has seized the Eagle S, a Cook Islands-flagged oil tanker, as part of an investigation into severe damage to underwater cables in the Baltic Sea.

NATO allies met on Dec. 30 to address the security of critical infrastructure in the Baltic Sea, following damage to undersea cables connecting Estonia and Finland several days earlier.

Police and media reports say that Finnish authorities have detained a Russia-linked ship as they investigate whether it damaged a Baltic Sea power cable and several data cables.

NATO member states have decided to enhance the bloc’s military presence in the Baltic Sea. The decision was made to protect critical infrastructure following recent damage to underwater cables connecting Estonia and Finland,

A power cable connecting Finland and Estonia under the Baltic Sea suffered a power outage on Wednesday, prompting an investigation.