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The new Russian Kilo-Class submarines are thought to be tracking Britain’s fleet throughout the North Atlantic - and may even be accessing under-sea internet cables, military sources claim. HMS Queen Elizabeth, the Royal Navy’s newly commissioned aircraft carrier, along with Britain’s Trident-carrying nuclear submarines are thought to be among those under surveillance.

Six of the Varshavyanka-class subs have already been launched, with another six likely to be deployed by the Russian navy by the end of 2019. All boast stealth technology, extended combat range and an ability to strike targets above and below the water, and also as on land. They are armed with a fearsome array of weaponry, including 18 torpedoes, sea mines and cruise missiles.

Russian submarines are operating undetected in British waters, experts have claimed

HMS Queen Elizabeth may be being monitored

A senior military source told the Telegraph: “The new First Sea Lord needs to deliver the underwater battle. We must be better at what we do. “The Russians are benefiting from a huge increase in research and development spending 15 to 20 years ago which is now producing this new class of super-quiet Kilo Submarines.” The submarines have been designated as ‘Improved Kilo-Class’ by NATO. JUST IN: Royal Navy scrambled after Russian warship spotted travelling through English channel

The subs can hit targets above or below sea, or on land

HMS Montrose protects British waters

“I also think we need to do more to respond to a changing world where there is more competition [and] greater risk of state-on-state conflict.” Speaking last year, then-defence secretary Gavin Williamson stressed the need for Britain to strengthen its defences in the face of “increasing aggression” from a “resurgent Russia”. He told naval experts at the Royal United Services Institute (RUSI): “We’re rapidly having to come to terms with this new age of warfare. Look at Russia’s resurgence under President Putin.

Vladimir Putin is thought to be testing UK defences

A map showing the locations of the world's nuclear weapons

“Its submarine activity has increased 10-fold in the North Atlantic. “That’s not all. In 2010, the Royal Navy had to respond once to a Russian Navy ship approaching UK territorial waters. “Last year we had to respond 33 times. “It goes to show the increasing aggression, the increasing assertiveness of Russia, and how we have to ensure we give the right support to our Royal Navy in order to give them the tools to do the job and keep Britain safe.”

Gavin Williamson has previously warned about Russian "aggression"