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.

NATO Secretary-General Mark Rutte on Friday said the alliance will increase patrols in the Baltic Sea region after Finland seized an oil tanker suspected of having damaged undersea power and internet cables this week.