Japan said Wednesday that its military scrambled fighter jets a record 340 times in the three months to June in response to feared intrusions on its airspace, as tensions grow with China.

The Joint Staff of Japan Self-Defense Forces said, however, that around 70 percent of the jet launches were in response to Russian planes approaching Japanese airspace.

The rest were scrambled in response to approaching Chinese planes, it said, adding that Japanese airspace was not violated on any of these occasions.

The latest figure marked a sharp increase on the same quarter last year, when Japanese jets were scrambled 110 times.

"The chief factor for the increase was the rise in (the number of launches) in response to Russian planes," the military said, particularly along Japan's northern coastline.

"Scrambles were often against information-gathering planes from Russia and fighter jets from China."

Russia frequently dispatches jets near Japan, as the two nations continue to negotiate a territorial dispute dating back to World War II.

Japan and China, meanwhile, are also locked in a bitter territorial row over islands in the East China Sea administered by Japan as the Senkaku Islands, but which China calls the Diaoyu Islands.

Chinese government ships and planes have been seen off the disputed islands numerous times since Japan nationalised some of them in September 2012, sometimes within the 12 nautical-mile territorial zone.