TOKYO - Japan warned Tuesday that China's "dangerous acts" over territorial claims in the East China Sea could lead to "unintended consequences" in the region, as fears grow of a potential military clash.
The comments appeared in an annual defence white paper approved by Prime Minister Shinzo Abe's cabinet, with the report heaping criticism on Beijing's unilateral declaration of an Air Defence Identification Zone (ADIZ) late last year.
The ADIZ - which overlaps on territory claimed by Japan - sparked regional criticism as well as condemnation from Washington, while commentators have voiced concern over the possibility of an armed conflict between the Asian powers.
Tokyo's paper noted that China's military budget had quadrupled over the past decade on the back of an "increasingly severe" security environment.
"Japan is deeply concerned about the establishment of 'the East China Sea ADIZ' which is a profoundly dangerous act that... escalates the situation and may cause unintended consequences" in the region, the 505-page paper said.
The zone required aircraft flying through China's zone to identify themselves and maintain communication with authorities, but it was not a claim of sovereignty.
Chinese vessels and aircraft have regularly approached an East China Sea archipelago claimed by both countries after Tokyo nationalised some of the chain in 2012.
The strategically important islands, believed to harbour vast natural resources below their seabed, are called the Diaoyu by China and Senkaku in Japan.
In a confrontation earlier this year, Tokyo said that two Chinese fighter jets flew within 30 metres (100 feet) of its aircraft in an area where the nations' air defence zones overlap.
Beijing responded that it was Japanese military planes that flew dangerously close to its aircraft.
Several Southeast Asian nations are also at loggerheads with China over separate territorial disputes in the South China Sea.
Relations between China and Vietnam plunged to their lowest point in decades when Beijing moved a deep-sea oil rig into disputed waters in the South China Sea in early May, triggering deadly riots in Vietnam.