NATO member Estonia has deployed a naval warship to defend its underwater power cables after a Russian vessel allegedly cut one of the wires in yet another act of sabotage against the allied nations.

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.

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 cables, 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.

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.

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.

Nato will bolster its military presence in the Baltic Sea after the suspected sabotage of an undersea power cable linking Finland and Estonia this week, the Western military alliance’s chief Mark Rutte said on Friday.