Tokyo's controversial governor wants to use public funds to buy islands disputed between Japan and China, a plan bound to infuriate Beijing.
The islands, known as Senkaku in Japan and Diaoyu in China, have long been the centre of maritime territorial disputes between China and neighbours both citing historical and other claims over fishing areas and potential rich gas deposits.
Shintaro Ishihara, 79, announced the idea of buying the uninhabited islands in the East China Sea from private owners during his visit to Washington and the Tokyo metropolitan government confirmed the plan on Tuesday.
In a statement citing Ishihara, the Tokyo government said the islands were extremely important for Japan and offered great potential for development of natural resources and fisheries.
Japanese government spokesman said he was not aware of the plan and declined further comment.
A Chinese Foreign Ministry news official told Reuters by telephone it had no information to offer regarding the plan.
Diplomatic ties between Beijing and Tokyo hit a low point in late 2010 after Japan's arrest of a Chinese fishing boat captain near the disputed islands, though they have improved since then.
In 2008, Beijing and Tokyo agreed in principle to jointly develop gas fields near the islands, but progress has been slow and Japan has accused China of drilling for gas in violation of the deal.
Kyodo news agency quoted Ishihara as saying that talks with owners were already under way and that a deal could be wrapped up by the end of the year.
Ishihara, elected for a fourth term a year ago, is no stranger to controversy, admired by some for his blunt style, a rarity in Japan, and lambasted by others for a tendency to offend.
Last year, he was forced to apologise for suggesting that the March 11 earthquake and tsunami were divine punishment for the egoism of the Japanese people.
(Reporting by Kaori Kaneko; Additional reporting by Sui-Lee Wee in Beijing; Writing by Tomasz Janowski; Editing by Nick Macfie)