Controversial Tokyo governor Shintaro Ishihara provoked an angry reaction from China Tuesday after saying taxpayers in Japan's capital will buy a small chain of uninhabited islands at the centre of a damaging territorial dispute.

Ishihara, an outspoken critic of Beijing who has made a career out of provocative nationalistic remarks, said he has approached the owner of the islands in the East China Sea, called Senkaku in Japan and Diaoyou in China.

"Tokyo has decided to buy them. Tokyo will defend the Senkaku islands," he told the conservative Heritage Foundation in Washington on Monday.

The remarks sparked an angry response from China, which vigorously claims the islands as its own, with foreign ministry spokesman Liu Weimin saying any unilateral action taken by Japan would be illegal.

"The Diaoyu Island and its affiliated islands have been part of China's territory since ancient times and China has indisputable sovereignty over them," Liu was quoted by state news agency Xinhua as saying.

If realised, the move would mark a new stage in the long-rumbling dispute over the islands, which sit around 2,000 kilometres (1,250 miles) from Tokyo in rich fishing grounds that may harbour lucrative energy resources.

Ishihara said he had begun negotiations to purchase Uotsurijima, Kitakojima and Minamikojima islands in the uninhabited island chain, which is owned by a Japanese family and leased to the Japanese government.

The islands are owned by the Kurihara family who bought them decades ago from descendants of the previous Japanese owners.

The online edition of the conservative Sankei Shimbun reported that the owners had agreed to sell to the Tokyo government.

Ishihara will hold hearings with experts and seek the agreement of the local legislature in his bid to buy the islands when the annually-renewable leases to the national government expire at the end of March, the Sankei said.

Relations between Tokyo and Beijing plunged in September 2010 when Japan's coastguard detained a Chinese fishing boat captain who rammed a patrol near the islands.

China cut off exports of rare earth minerals vital to high-tech manufacture and halted political and cultural exchanges forcing Japan into what was widely seen as a humiliating climbdown and releasing the captain.

The two sides have since worked to patch up relations and sought to avoid the subject on the diplomatic stage.

But Ishihara, whose blunt approach to international relations has long been a thorn in the national government's side, appears determined to keep the issue alive.

He did not discuss the expected cost of the islands, saying only they would be "not too expensive".

Ishihara is expected to address the media after he returns from the United States on Thursday.