The Japanese air force scrambled 24 planes, including F-15 fighters and an E-767 radar plane, to intercept the Russian aeroplane.
  
'Warnings ignored'

According to a defence ministry statement, air force personnel gave "a notice, then a warning and another a notice and a warning".

"All flights of the Russian air force were carried out in accordance with international air space regulations without breaching the other states' borders"

Alexander Drobyshevsky, Russian air force spokesman
"There was no response."
  
The plane then flew back north towards the Russian island of Sakhalin.

However, Alexander Drobyshevsky, a Russian air force spokesman, said: "All flights of the Russian air force were carried out in accordance with international air space regulations without breaching the other states' borders."

The aircraft were accompanied by Japanese and US war planes, Russia said.
   
The TU-95, Russia's longest serving bomber, is capable of carrying AS-15 "Kent" cruise missiles which can deliver a nuclear warhead.

The air force did not say if the aircraft involved were carrying live weapons.

'Serious modernisation'

The Tupolev design bureau said last year it had begun a "serious modernisation" of the TU-95 strategic bomber.

Russia last violated Japanese air space in January 2006, when a Russian plane flew over Rebun Island,  off the coast of Hokkaido, an island in the north of the country.

Japan and Russia have never signed a peace treaty to formally end the second world war due to a dispute over four islands off Japan's  northern coast seized by Soviet troops in 1945.

Vladimir Putin, the Russian president, announced in August of the  resumption of long-range flights in international air space which were abandoned in 1992 due to financial difficulties following the collapse of the Soviet Union.

Last week, 14 long-range bombers flew over the north Atlantic in the latest of a series of military manoeuvres held off Europe's coastline since December, Russian media reported.