MOSCOW, Aug. 15 (Xinhua) -- An RC-135 reconnaissance plane of the British Royal Air Force illegally crossed Russia's state border in the Arctic area of Cape Svyatoy Nos, the Russian Defense Ministry said on Monday.

The British aircraft was discovered over the waters of the Barents Sea, and a MiG-31BM fighter scrambled in response and forced the plane out of the Russian territory, the ministry said.

It was rare for military planes of the North Atlantic Treaty Organization to breach Russia's airspace, news reports said.