China’s growing military might means it now poses a greater threat to Japan than North Korea, the government in Tokyo has suggested.

The Japanese government’s annual defence review, which was published on Thursday, said the People’s Republic is rapidly closing its military capability gap with the United States and projecting its influence into the western Pacific with increasing assertiveness.

But a worrying lack of transparency about its intentions and an increase in long-range bomber flights and naval exercises near Japan “represent a serious security concern for the region,” the report said.

"The reality is that China is rapidly increasing military spending," Defence Minister Taro Kono said at a media briefing. "China is deploying air and sea assets in the Western Pacific and through the Tsushima Strait into the Sea of Japan with greater frequency."

China hit back at the report. Geng Shuang, a Chinese foreign ministry spokesman, said the country would not accept “"groundless criticism" of its normal national defence and military activities.

The annual White Paper painted a worrying picture of mounting tension and discord in east Asia, confirming for the first time that North Korea has miniaturised nuclear warheads that can be mounted on missiles.

Analysts said the decision to devote its second chapter after the one on the United States, Japan’s main ally, to China indicated a shift in the hierarchy of perceived threats.