MINISTERS have been warned the country has been left "dangerously exposed" after it emerged Britain had to seek foreign assistance to help hunt for a submarine off the west coast of Scotland.

Maritime patrol aircraft (MPAs) from the US, Canada and France carried out patrols alongside British surface warships in the search for the submarine, believed to be from Russia, in late November and the first week of December, operating out of RAF Lossiemouth in northern Scotland.

The operation has been dubbed The Hunt for the Red December after Tom Clancy's Cold War submarine thriller which was turned into a successful movie starring Sean Connery.

The search began when a periscope was sighted in waters where British submarines would normally surface as they head into or out of the Royal Navy's submarine base at Faslane.

It is understood that at the height of the hunt four allied patrol planes flew to RAF Lossiemouth to join the search.

The incident came a month after another suspected Russian submarine was spotted off Sweden's Stockholm archipelago, and as relations with Moscow are at their frostiest since the Cold War.

Last month, the Royal Navy tracked four Russian warships passing through the English Channel.

On this occasion, the Ministry of Defence (MoD) said the ships had been escorted out of UK waters by Royal Navy warship HMS Tyne.

Last year, it was believed the Navy was shadowing at least one Russian naval vessel off the coast after it sailed into the Moray Firth while on exercise on the North Sea.

There was a similar incident in December 2011 when several ships from the Baltic Fleet arrived 30 miles off the Moray Firth, including the huge aircraft carrier Admiral Kuznetsov, the anti-submarine warfare ship Admiral Chabanenko and escort the Yaroslav Mudry.

The Russian military news agency Interfax-AVN reported at the time that the fleet was on route to Syria and took shelter in the Moray Firth when faced with deteriorating weather conditions.

But some analysts believe that Russia has been testing Britain's response times to such incursions.

The SNP are critical of the scrapping of the Nimrod fleet which has left the UK with no dedicated maritime patrol aircraft. The party says it has now become deeply concerned about the latest developments.

The SNP also highlight the fact that there are no warships based in ­Scotland to respond to such incidents. They also raised concerns that defence cuts have left the UK with a much-diminished maritime surveillance capability.

Britain has not sent a single ship to SNMG2, Nato's standing maritime immediate reaction force, since HMS Chatham and HMS Montrose were assigned four years ago. The latest Sea Breeze exercise in the Black Sea to bolster Ukrainian security had no Royal Naval participation.

The party's Westminster leader and defence spokesman, Angus Robertson MP, said: "The latest reports of foreign naval activity deep into Scottish waters are alarming but not infrequent.

"The funding for conventional defence in Scotland has been cut to the bone - without a single large surface ship based there and no maritime patrol aircraft at all leaving us dangerously exposed.

"The UK likes to trot out that it punches above its weight - but allies know this to untrue as they continually have to come to the UK's aid providing basic conventional capability to fill the chasm these cuts have caused."

An RAF Sentinel radar-reconnaissance aircraft is understood to have been one of the planes said to have taken part in the latest operation which appears finally to have drawn to a close - although it is unclear whether the sub was spotted by allied forces and moved, or whether it left Scottish waters of its own accord.

Robertson said: "The UK frequently has no proper ship assigned to protect its waters - known as the Fleet Ready Escort - and when it does it is based in the south of England, away as far as possible from most of the activity it would need to monitor.

"It also has not provided a single warship to the NATO North Atlantic patrol group for five years - which is the backbone of common naval defence in the North Atlantic.

"The UK Government's dual obsessions with foreign illegal wars and nuclear weapons has meant that funding has gone to operations "out of area" and to weapons of mass destruction that can never be used. Projecting power abroad is apparently more important than defending your exclusive economic zone and co-operating with your neighbours."

Poland's defence minister Tomasz Siemoniak warned on Friday that Russian naval and airforce activity has reached "unprecedented" levels and that the majority of incidents involved operations in international waters.

Siemoniak said Poland sees Russia's show of military strength primarily as an attempt to test Nato, adding that "it doesn't help to build good relations and trust."

Robertson added: "Scotland is in the key geo-strategic location bridging the Arctic and the North Atlantic. The UK has totally failed to grasp this.

"The High North will only grow in importance with increased competition for resources and shipping through the Northern routes - which can be hugely beneficial to Scotland but also pose serious environmental challenges. Decisions about these matters are best taken in Scotland where they would prioritise the proper protection of its territory."

The MoD said in a statement: "Nato partners have provided assistance for the operation of maritime patrol aircraft from RAF Lossiemouth for a limited period with the Royal Navy. We do not discuss the detail of maritime operations."

The Royal Canadian Air Force confirmed that following a request for assistance from the UK, the Canadian Armed Forces "deployed one CP-140 Aurora Aircraft to RAF Lossiemouth for a limited time".

In May 2007, Tornado F3 jets from RAF Leuchars in Fife were sent to intercept two Russian aircraft spotted observing a Royal Navy exercise over the Western Isles.

They were identified as Tupolev Tu-142 Bear Foxtrot planes, commonly seen by RAF pilots during the Cold War and which feature in The Hunt For Red October.

The Russian aircraft were escorted from the area by the RAF, who said no radio contact took place between the pilots, before returning to their base in Murmansk.

Nato announced last month that it had scrambled warplanes 400 times so far this year in response to increased Russian air activity around Europe.

An MOD spokesperson said: "Tough decisions had to be taken in order to rebalance the Defence budget; this included removing the Nimrod MR2 from service. However, maritime surveillance is provided through a combination of layered capabilities including surface ships, submarines, and various air assets. The UK continues to work closely with its Nato allies, and last week a number of partners provided assistance in the operation of Maritime Patrol Aircraft from RAF Lossiemouth for a limited period alongside the Royal Navy."