A Norwegian-owned and Russian-crewed ship that authorities initially suspected may have been involved in damage to an underwater fiber optic cable connecting Latvia and the Swedish island of Gotland has been released.

Norwegian authorities have released a cargo ship with an all-Russian crew, initially suspected of damaging a Baltic Sea telecoms cable. After investigation, no connection was found between the ship and the incident.

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.

A Norwegian ship suspected of being involved in "serious damage" to an underwater telecoms cable between Latvia and Sweden has been boarded by police.

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.

The Nordic country has opened an investigation into the damage, just weeks after NATO stepped up its military presence in the area following a series of similar incidents.

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.