The Japanese government accused China of violating its airspace Thursday morning, after Chinese maritime surveillance planes flew near the islands disputed by the two powers.

China's Xinhua news agency confirms that Chinese planes were sent to patrol the territorial waters surrounding the disputed Diaoyu Islands (Senkaku in Japanese) at around 10:00 A.M. Thursday.

Xinhua cites China's State Oceanic Administration as saying the B-3837 plane joined a fleet of four surveillance ships that are stationed near Japanese territorial waters.

Japanese broadcaster NHK reports that Japan deployed eight F-15 fighter jets and an early warning aircraft in response to the sighting off Uotsuri Island.

Senkaku/Diaoyu Islands in the East China Sea (Screenshot from GoogleMaps)

"Despite our repeated warnings, Chinese government ships have entered out territorial waters for three days in a row," Japanese Chief Cabinet Secretary Osama Fujimura told Japanese daily the Asahi Shimbun Thursday.

"It is extremely regrettable that, on top of that, an intrusion into our airspace has been committed in this way," he said.

Relations between the two countries have become ever more strained since the Japanese government bought the islands in the East China Sea from a private Japanese owner in September. Both China and Taiwan also claim the islands as part of their own respective territories.

"The Diaoyu islands and affiliated islands are part of China's inherent territory. China's flight over the islands is completely normal," Chinese Foreign Ministry spokesman Hong Lei told reporters in Beijing.

"The Chinese side calls on Japan to halt all entries into water and airspace around the islands." 

The incident also comes just days before a general election in Japan, when the Liberal Democratic Party (LDP) is expected to return to power, headed by former prime minister Shinzo Abe, who is noted for his staunch nationalism.