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.

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.

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

The Central Criminal Police has not yet found evidence that Russian special services are behind severing the Finland-Estonia underwater cable. However, the incident prompted NATO to launch the Baltic Sentry mission.

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.

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,

Estonia’s defence minister proposed on Wednesday that shipping companies may have to pay a fee to use the Baltic Sea, one of the world’s busiest shipping routes, to cover the high costs of protecting undersea cables following a series of breaches,