Japan's military scrambled a record number of jets last year mostly in response to an increase in approaching Chinese aircraft, the government said Thursday.

Tokyo ordered its jets to the skies 1,168 times in the fiscal year through March, the defence ministry said, with 73 percent of the missions against aircraft either known to be or believed to originate from China.

"Activities of Chinese jets are on the rise in terms of their frequency, area, and duration," said Admiral Katsutoshi Kawano, head of Japan's joint chiefs of staff.

"Considering the modernising trend of the Chinese military, we expect this to continue," he told a press conference.

The total number of scrambles marked an increase of 295 from the year before, the ministry said, noting that none of the cases resulted in violations of Japan's airspace.

Japan and China are at odds over a set of uninhabited islands in the East China Sea that sit in rich fishing grounds.

The islands, known as the Senkakus in Japan and the Diaoyus in China, are a running sore in Tokyo's relations with Beijing.

Japan has administrative control of the islets but China claims they have been part of its territory for centuries.

The two countries have clashed diplomatically over their ownership, with both sides sending ships and aircraft to nearby waters to assert their claims.

Japanese officials believe China has been trying to analyse the capacity and response patterns of Japan's defence and coastguard personnel.