Britain's air force scrambled four Tornado warplanes to intercept eight Russian long-range bombers, but the Russian planes did not enter British air space, the Ministry of Defence said.
Russia's Defence Ministry said 14 strategic bombers had been flying long-range patrol operations but none approached a foreign state and most were accompanied by fighter jets from NATO countries.
Relations between Britain and Russia are at their worst since the Cold War, but the Foreign Office said Britain did not see a recent Russian decision to resume of long-range patrols as a cause for alarm and that "normal preparedness" was in place.
Russia's refusal to extradite Andrei Lugovoi, a former KGB bodyguard suspected of murdering emigre Alexander Litvinenko in London last year, led to tit-for-tat expulsions of diplomats this year.
"In the early hours of this morning four RAF (Royal Air Force) Tornado F3 aircraft... were launched to intercept eight Russian Bear aircraft which had not entered UK air space," the Ministry of Defence said in a statement.
A British Foreign Office spokesman said relations with Russia "continue as normal outside the unresolved extradition request".
The Tupolev Tu-95, code-named 'Bear' by NATO, is Russia's equivalent of the US B-52 bomber and is a Cold War icon.
Russia's Defence Ministry said 14 Russian strategic bombers had started long-range routine patrol operations on Wednesday evening over the Pacific, the Atlantic and the Arctic.
"The planes flew only over neutral water and did not approach the air space of a foreign state," it said.
"Practically all the planes were accompanied by fighters from NATO countries."
It is at least the second time in recent months Britain has scrambled jets to intercept Russian bombers.
The sorties by Russian bombers appeared to the latest of the regular long-range patrols that President Vladimir Putin announced last month would be resumed, after a gap following the collapse of the Soviet Union.
- Reuters
F-16 fighter jet 
Four F3 Tornado fighter jets were launched by the United Kingdom's Royal Air Force to intercept Russian military planes. The eight Russian jets were flying in airspace patrolled by Nato, officials from the UK claimed. The long-range bombers were initially followed by Norwegian F16 jets, after Russia's recent decision to reinstate Cold War-style long-range patrols. 

14 strategic bombers were flying on long-range patrol, according to Russia's Defence Ministry. They also confirmed that none had approached a foreign state and had been shadowed by aircraft from Nato countries.  

The Ministry of Defence in the United Kingdom released a statement that the Russian Tupolev Tu-95 Bear aircraft, flying in four loosed pairs, were tracked by Norwegian aircraft before entering Nato airspace on Thursday morning. The UK currently holds responsibility for the Nato airspace, and launched four F3 Tornados from RAF Leeming in North Yorkshire, UK, to identify the bombers. The bombers eventually left the Nato zone, under tracking by UK aircraft and RAF radar in Northumberland. 

An MoD spokesman confirmed that Russia was entitled to its long-range patrols, adding 'The motivation behind any Russian military activity is a matter for the Russian government.' Lt Col John Inge Oegland, spokesman for the Norwegian armed forces, said there had been several similar incidents in recent months, but that the Russian flights were not causing alarm in Norway. 

Relations between Britain and Russia have worsened recently, particularly after Russia's refusal to allow the extradition of a former KGB bodyguard suspected of murdering emigre Alexander Litvinenko in London last year. Relations with Russia would "continue as normal outside the unresolved extradition request", a UK Foreign Office spokesman said.