Police say a Norwegian-owned and Russian-crewed ship that authorities suspect may have been involved in damage to an underwater fiber optic cable connecting Latvia and the Swedish island of Gotland has been stopped off Norway.

The authorities said they believed the vessel may have been involved in damaging the cable, the latest act of apparent sabotage in the Baltic Sea.

The NATO military alliance is ramping up efforts to protect undersea cables in the region amid growing concerns of Russian sabotage and spying. View on euronews

NATO is ratcheting up its guard against suspected attempts to sabotage underwater energy and data cables and pipelines that crisscross the Baltic Sea.

After a series of suspected undersea cable cuttings, NATO has launched a new surveillance and deterrence mission to protect critical infrastructure under the Baltic Sea.

Norwegian police say they had seized and boarded a Norwegian ship with an all-Russian crew on suspicion of involvement in causing damage to a telecoms cable in the Baltic Sea, the second vessel to be named by investigators in the case.

Nato countries have stepped up patrols to protect critical underwater infrastructure in the Baltic Sea, which is bordered by eight countries, and other waters. A Royal Navy submarine was ordered to surface last November close to a suspected Russian spy ship which was loitering over undersea infrastructure in UK waters.

Estonia's defence minister on Wednesday said ships may have to pay a fee to use the Baltic Sea to cover costs of protecting undersea cables.

Baltic Sea as part of a mission to protect undersea cables and pipelines. As authorities investigate the fourth Baltic Sea cable-cutting incident in recent months, European leaders have expressed concern about the frequency of attacks involving civilian vessels and critical civilian infrastructure.