Part of the disputed islands in the East China Sea, known as Senkaku in Japan and Diaoyu in China.

Part of the disputed islands in the East China Sea, known as Senkaku in Japan and Diaoyu in China. Photo: Reuters

Tokyo: Chinese fighter jets flew within a few dozen metres of Japanese military planes over the East China Sea, Japanese officials said, prompting the Defence Minister to accuse Beijing of going "over the top" in its approach to disputed territory.

The Chinese jets came as close as 50 metres to a Japanese surveillance plane near disputed islets on Saturday and within 30 metres of an electronic intelligence aircraft, the ministry said on Sunday.

"Closing in while flying normally over the high seas is impossible," Defence Minister Itsunori Onodera told reporters in comments broadcast on TV Asahi. "This is a close encounter that is outright over the top."

Anti-Chinese protesters in Vietnam rally against Beijing's deployment of an oil rig in the contested waters of the South China Sea.

Anti-Chinese protesters in Vietnam rally against Beijing's deployment of an oil rig in the contested waters of the South China Sea. Photo: AP

Mr Onodera said Japan conveyed its concerns to China through diplomatic channels. He also said the Chinese planes were carrying missiles.

A ministry official said it was the closest Chinese warplanes had come to aircraft of Japan's self-defence force.

China's Foreign Ministry could not be immediately reached for comment.

Tensions have been running high between China and its neighbours over Beijing's assertive stand on claiming land and sea territory. China lays claim to Japanese-administered islets in the East China Sea, known as Senkaku in Japan and Diaoyu in China. It is also pressing its claim to almost all the South China Sea, brushing aside claims by several south-east Asian states.

China's proclamation last November of an air defence zone covering disputed islands and areas in the South China Sea have raised concerns that a minor incident in disputed areas could quickly escalate.

Sino-Japanese ties have long been strained by allegations in China that Japan has not properly atoned for its wartime aggression and by the spat over the uninhabited islands.

Japanese land, sea and air forces joined last week to simulate the recapture of a remote island, underscoring Tokyo's concerns about the security of the islets.

Tensions between China and its neighbours have also risen sharply in the South China Sea in recent weeks, following the deployment of a Chinese oil rig in waters also claimed by Vietnam. The deployment sparked anti-Chinese riots in Vietnam.

The Philippines foreign ministry this month accused China of reclaiming land on a disputed reef in the South China Sea and said it appeared to be building an airstrip.

Reuters