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.

In just three months, three incidents of damage to Baltic Sea underwater cables have taken place. While accidential cable slices are common, the cluster raises suspicion.

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.

Shipping firms may need to pay a fee to use the Baltic Sea, one of the world's busiest shipping routes, in order to cover the high costs of protecting undersea cables, Estonia's defence minister said on Wednesday following a spate of breaches.

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.

An undersea data cable between Latvia and Sweden was damaged early on January 26, the latest in a series of similar incidents in the Baltic Sea in which critical seabed energy and communications lines are believed to have been severed by ships traveling to or from Russian ports.