Japan scrambled fighter jets Thursday after a Chinese plane flew into its airspace over the disputed East China Sea islands, a media report said.
Japan mobilised F-15 jet fighters when a Chinese Oceanic Administration plane was spotted, said government spokesman Osamu Fujimura, BBC reported.
The islands, called Senkaku in Japan and Diaoyu in China, have been a source of tension.
The Chinese aircraft was seen at around 11 a.m., Fujimura said.
Japan's coast guard reported that Chinese surveillance ships were seen in waters near the islands earlier in the day.
Relations between the two countries have plummeted over their claims to the islands.
Japan claims it has occupied the islands since 1895, while China maintains the islands were recognized as Chinese as early as 1783.
The islands, which are also claimed by Taiwan, potentially contain large reserves of hydrocarbons.
The tension between the two Asian powers boiled over again after Japan announced in September the purchase of three of the islands of the disputed island chain, which sparked violent anti-Japan protests in a number of Chinese cities that in turn led to the suspension of events commemorating the 40th anniversary of the two countries' renewal of diplomatic ties and forced many Japanese companies in China to suspend operations temporarily.