Beijing on Thursday dismissed Japan's complaints of a Chinese military aircraft flying through international airspace near Japan's southern islands, saying it was not the first time a Chinese aircraft had conducted legal training in the western Pacific.

The flyover on Wednesday was part of the Chinese navy's routine training and "does not target any specific country or have any specific aim", Geng Yansheng, a defense ministry spokesman, said at a monthly news conference.

"The training is in accordance with international law and practice, and China has the legal right and freedom of flight over the relevant seas," he said. "We have had several such training exercises there before."

Japan's Defense Ministry on Wednesday scrambled fighter jets to keep watch on a Chinese Y-8 early-warning plane flying over international waters between Okinawa's main island and an outer island relatively close to the Diaoyu Islands, which both countries claim, in the East China Sea.

Japanese Defense Minister Itsunori Onodera said on Wednesday that the flight was "a sign of China's escalating maritime advance".

Japanese Prime Minister Shinzo Abe, before leaving for Malaysia, Singapore and the Philippines, where he was believed to discuss ways to contain China, said: "It was an unusual action that we have never seen before. We'll keep monitoring with great interest".

China-Japan ties have been strained since Tokyo illegally "nationalized" part of the Diaoyu Islands last September.

Observers said Japan is flaring up "Chinese threats" as an excuse for beefing up military power, and has increased the risks of conflict by challenging Chinese legal rights in international airspace and high seas.

Xing Guangmei, a Beijing-based military expert, said: "Japan's monitoring is an unfriendly move and may cause clashes if its planes get too close to the Chinese plane," she said.

Also on Wednesday, Japan's coast guard said they spotted four Chinese coast guard vessels near the Diaoyu Islands.

"Tokyo is making a fuss of almost all Chinese activities in the sea to force China to give up its sovereignty, but China's growing strength will allow it to send more military forces to safeguard its legitimate interests," Xing said.

Gao Hong, a professor at the Chinese Academy of Social Sciences, said: "China is not responsible for Japan's unnecessary concerns since it is Japan, or rather its right-wing forces, that is playing the China card to woo support at home and abroad for its moves to break post-war restraints, including amending its pacifist constitution and developing a regular army."

Mo Jingxi and Reuters contributed to this story.

zhaoshengnan@chinadaily.com.cn