Chinese and Japanese aircraft were involved in a standoff in the skies above the Diaoyu Islands on Thursday.

The situation remains under control, but Tokyo seems intent on upping the ante, observers said.

A Chinese marine surveillance plane, B-3837, was sent to join vessels patrolling the territorial waters around the islands, which belong to China, on Thursday morning, said a statement issued by the State Oceanic Administration on its website.

A Chinese marine surveillance plane, B-3837, conducts joint patrols with a fleet of four surveillance ships in the territorial waters around the Diaoyu Islands, which belong to China, on Thursday. [Photo/Xinhua]

The plane arrived in the area at about 10 am and conducted joint patrols with a fleet of four surveillance ships.

The fleet ordered the Japanese ships that had entered China's territorial waters to leave the area immediately, the statement said.

Warned by the Japanese coast guard, the Chinese aircraft responded that it was flying in Chinese airspace, Japan's JiJi Press quoted the coast guard's 11th regional headquarters in Naha, Okinawa Prefecture, southern Japan as saying.

The Japanese Air Self-Defense Force scrambled F-15 fighter jets to the area, Japan's Kyodo News Agency reported.

The Yuzheng 206, China's largest fishery patrol ship, at port in Shanghai on Tuesday. The vessel embarked on its maiden voyage from Shanghai on Tuesday to patrol waters near the Diaoyu Islands, showing China's determination to safeguard its sovereignty over the islands. [Photo/Xinhua]

Japan's Defense Ministry accused the air patrol of an "airspace intrusion".

Japan's Vice-Foreign Minister Chikao Kawai summoned Chinese diplomat Han Zhiqiang to the Foreign Ministry in the early afternoon to lodge a protest, according to the Kyodo News.

Han asserted that the islands belong to China and declined to accept the protest. The diplomat noted that China hopes to resolve the dispute in a peaceful manner through communication between the two countries.

It was the first "incursion'' by a Chinese aircraft into "Japanese airspace" since Tokyo began monitoring in 1958, Japan's Defense Ministry said.

The Chinese Foreign Ministry on Thursday blasted the Japanese F-15 fighters' attempt to intercept the Chinese patrol plane.