TOKYO (Reuters) - Japan's air defense force scrambled its fighter jets in response to Chinese military aircraft at a record rate in the six months ended Sept. 30, raising the number of such incidents from a year ago by about three-quarters.

In the six months to the end of September, fighters scrambled to chase Chinese planes 407 times compared with 231 times in the same period last year, according to a press release from the Japanese Air Self Defence Force

Encounters with Russian aircraft, which are often bombers that fly around Japan from the north skirting its airspace, rose 67 percent to 180.

Japan worries that as China increases its control over the South China Sea it is turning its attention to expanding its influence in the East China Sea and into the western Pacific, where Japan controls a chain of islands stretching 1,400 km (870 miles) from the country's mainland south towards Taiwan.

At the current rate of total scrambles, which stood at 594 at the end of September, the number for the year to March 31, 2017, will exceed the 944 encounters logged 30 years ago at the height of the Cold War.

(Reporting by Tim Kelly and Nobuhiro Kubo; Editing by Tom Hogue)