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 said on Friday it would boost its presence in the Baltic Sea after the suspected sabotage this week of an undersea power cable and four internet lines, while alliance member Estonia launched a naval operation to guard a parallel electricity link.

A power cable connecting Finland and Estonia under the Baltic Sea suffered a power outage on Wednesday, prompting an investigation, according to the Finnish prime minister. The electrical transmission through the Estline 2 connection between the two European nations was cut on Wednesday afternoon local time.