Fighter pilots scrambled from RAF Leuchars in Fife could have been forgiven for thinking they had been thrown 20 years back into a Cold War timewarp.

The British airmen were still at primary school the last time the UK's sentinel radar showed "Bears in the Air" over the North Sea and the station klaxon sounded what might well have been the warning notes for the Third World War's opening round.

The two Tornado F3s interceptors swiftly found themselves flying in close formation with a pair of Russian Bear Foxtrot bombers - the legendary maritime raiders that regularly probed the UK's airspace when the Kremlin still flew the hammer and sickle of communism.

The Cold War-era aircraft had swept down from Murmansk from a base on the Kola Peninsula, in the far north of Russia, to snoop on Neptune Warrior, a Royal Navy exercise.

The exercise was staged in international waters off the Scottish coast over the past week and involved UK and allied warships.

The RAF would not disclose exactly when the brief incident to the north of the Outer Hebrides took place, but said no contact was made between Russian and British aircraft.

Squadron Leader Keith Wardlaw said he could not remember the last time such an encounter took place.

"The Russians obviously thought it might be worth coming through to have a look at what we were up to and probably take some photos," he said.

"It's a throwback to the Cold War when they used to fly in regularly to poke and prod at the edges of British airspace and test our reaction times.

"It's normal to let such aircraft know we're there by pulling up alongside them and they left quietly. The whole encounter probably lasted 15, 20 minutes."

Neptune Warrior was a live-fire naval training exercise involving warships, submarines and aircraft that took place between April 22 and last week.

The 161ft-long Bear Foxtrot was designed to fly 3975 miles without refuelling, carrying a payload of more than 10 tons - about the weight of a nuclear bomb at the time the plane was made.

Paul Jackson, editor of Jane's All The World's Aircraft, said: "This aircraft dates back to the 1950s and although the air frame might look dated it is still highly effective in terms of long-range maritime reconnaissance.

"These used to fly over the North Sea and the Greenland Gap daily during the Cold War and, while rare today, it's by no means a unique occurrence. It's nice to know the Russians are out and about again.

"The exercise was in international waters and the Russians have got just as much right to be there as we have. We do it to them, they do it to us.

"All the RAF is doing is telling them: We could do this for real if we wanted to, so go and tell your mates back home'."

Squadrons of long-scrapped Phantom interceptors were on constant quick-reaction standby through the 1970s and 80s to counter the threat of Soviet long-range bombers launching a sneak attack on northern airfields and the Royal Navy's submarine base at Faslane.

The Bears were also designed to carry an arsenal of missiles, some nuclear-tipped, to strike Nato warships blocking the entrance to the vital North Atlantic sealanes between the US and Europe.

Interceptions of a friendlier nature became common- place as superpower tensions thawed in the late-1980s. RAF and Russian aircrew would then hold up Playboy centrefolds against the cockpit canopies of their aircraft as they passed each other.