A RISING number of Russian naval vessels have been detected in UK waters including submarines caught "lurking" near the Faslane nuclear-armed submarine base, a foreign affairs think tank has found.

The Russian subs are thought to be attempting to identify the “acoustic signature” of Britain’s Vanguard submarines in order to track and potentially sink them before they can launch their nuclear missiles, according to the Henry Jackson Society.

Experts say the “alarmingly regular” contacts paint “a worrying picture of the revival of Cold War Russian habits of probing our defences by sea and, especially, by air”.

In one incident in August 2010, a Russian Akula-class Typhoon submarine stood off Faslane “waiting for a Trident-capable Vanguard-class submarine to leave the port for its three-month patrol.”

On two occasions in 2015, the UK was unable to deal with the threat posed by suspected Russian submarines positioned off the Scottish coast and had to seek assistance from Canada, France, and the United States, the society said.

Dr. Andrew Foxall, director of the society’s Russian Studies Centre, pieced together official air intercept statistics and media reports of naval contacts — which are not recorded by the MoD — and found a rise in Russian intrusions in UK territory.

There were 12 reported Russian naval approaches in UK seas between 2013 and 2016 — and just two in the previous seven years.

Over half of the 43 reported contacts by air and sea occurred between 2005 and 2016 occurred in the most recent three years.

The report said: “Russia’s submarines, which lurk off naval bases in Scotland, seek even…sensitive information: the ‘acoustic signature’ made by the UK submarine fleet, including the Vanguard submarines that carry Trident nuclear missiles.

“If Russia were able to obtain a recording of the ‘signature’, it would have serious implications for the UK’s nuclear deterrent: Russia would be able to track Vanguards and potentially sink them before they could launch their missiles.”

Scottish air bases were by far the busiest in the UK with nine launches from RAF Lossiemouth and seven from RAF Leuchars, which became an army base in 2014, compared with just two each from RAF Coningsby and RAF Leeming in England.

While the large number of North Sea contacts are largely down to geography, with routine Russian and UK routes straddling each other, some are thought to be deliberate shows of strength at times of international tension.

The murder of Alexander Litvinenko in November 2006 saw airspace incidents rise from four in 2005 to 19 in 2007, while an airspace incident in January 2008 coincided with a dispute over British Council’s operations in Russia which saw the closure of two of its three offices.

Two Russian bombers buzzed the Cornish coast the day after Ben Emmerson QC characterised Russia as a “mafia state” during the inquiry into Litvinenko’s death in 2015.

“In this sense, the incursions serve as a sabre-rattling sign of the Kremlin’s displeasure.”

Dr Foxall said: “There is a troubling picture of close encounters and emergency scrambles perpetuated by an aggressive Russian government…these Russian activities are best understood not in isolation, but rather as a part of the Kremlin’s increasingly assertive foreign policy toward the West.”

Dr. Julian Lewis, former chair of the House of Commons Defence Select Committee, said: “Dr Foxall paints a worrying picture of the revival of Cold War Russian habits of probing our defences by sea and, especially, by air.”

An MoD spokesman said: “We keep all threats under constant review and have robust security measures in place to combat them.

“This includes RAF Quick Reaction Alert Typhoon aircraft, a Royal Navy warship held at continuous high readiness and the ultimate guarantee of our security, the nuclear deterrent.”

The Russian Embassy in the UK declined to comment.