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.

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 defense minister said on Wednesday following a spate of breaches,

The Baltic Sea region is on high alert as fears grow that Russia could target undersea cables as part of a wider campaign of so-called "hybrid warfare".

Cables deep under the Baltic Sea keep getting damaged - here is what Nato is doing to protect them - Nato is deploying eyes in the sky and on the Baltic Sea to protect cables and pipelines

The alliance mounted its first coordinated response to a suspected sabotage campaign against critical infrastructure after another cable was severed in the Baltic Sea.

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.

With its powerful camera, the French Navy surveillance plane scouring the Baltic Sea zoomed in on a cargo ship plowing the waters below — closer, closer and closer still until the camera operator could make out details on the vessel's front deck and smoke pouring from its chimney.

So far, the impact on Europe’s natural gas, electricity and data flows has been fairly limited. But a concerted attack on data cables could paralyze many nations’ communications networks, jeopardizing hospital surgeries, police responses and more.

A subsea cable connecting Latvia to Sweden’s Gotland island is the latest cable to be damaged in the Baltic Sea. Owned by Latvia’s State Radio and Television Centre (LVRTC), the cable’s Ventspils–Gotland segment was damaged early on January 26, at depths of 100m.

Europes undersea infrastructure faces increasing disruptions, with gas pipelines, power lines, and data cables under threat. Recent damage to a critical cable between Sweden and Latvia adds to the series of incidents across the Baltic Sea.

Russia is "the main actor" in hybrid attacks on the alliance, said a senior NATO official following a spate of incidents.