Britain's air force scrambled four Tornado warplanes yesterday to intercept eight Russian long-range bombers, the Ministry of Defense said.

The ministry said the Russian aircraft had not entered British air space.

"In the early hours of this morning four RAF (Royal Air Force) Tornado F3 aircraft from RAF Leeming and RAF Waddington (bases) were launched to intercept eight Russian Bear aircraft which had not entered UK air space," it said in a statement.

The Tupolev Tu-95, codenamed "Bear" by NATO, is Russia's equivalent of the US B-52 bomber and is a Cold War icon.

Russia's defense ministry published a statement earlier yesterday which said 14 Russian strategic bombers had started long-range routine patrol operations on Wednesday evening over the Pacific, the Atlantic and the Arctic.

The statement said six planes had already returned to base and the other eight were still in the air.

"The planes flew only over neutral water and did not approach the air space of a foreign state," the statement said. "Practically all the planes were accompanied by fighters from NATO countries."

Lieutenant Colonel John Inge Oeglaend, of the Norwegian Joint Headquarters, said the Russian strategic bombers neared but did not enter Norwegian air space in the far north.

Oeglaend said two Norwegian F-16 fighters were sent up both times that the Russian aircraft approached Norway, in keeping with normal practice.

Relations between London and Moscow are at their worst since the Cold War. Russia's refusal to extradite Andrei Lugovoy, a former KGB bodyguard suspected of murdering emigre Alexander Litvinenko in London last year, led to tit-for-tat expulsions of diplomats from both countries.

Ties between Russia and the European Union have also deteriorated of late over issues such as energy policy, Kosovo and Moscow's treatment of European firms operating there.

Sky News said the Russian bombers were heading towards British air space and did a U-turn when approached by the British fighters. 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.