China warned Wednesday that Tokyo Gov. Shintaro Ishihara's plan to buy the disputed Senkaku Islands will not only harm Japan's ties with China but also its international standing.

"I want to reiterate that the Diaoyu Islands have been China's inherent territory since ancient times and China holds indisputable sovereignty over them," Foreign Ministry spokesman Liu Weimin told a regular news briefing, using the Chinese term for the Senkaku Islands.

"We do not wish such statements in Japan to encroach on China's sovereignty and harm China-Japan ties," Liu said. "A few politicians have repeatedly made such statements. I believe they not only damage the overall state of China-Japan relations but also harm Japan's international image."

Ishihara said in Washington on Monday that the Tokyo Metropolitan Government is negotiating with the owner of three major islands in the uninhabited chain.

On Tuesday, Ishihara added that Beijing's dispatch of fishery patrol boats to their vicinity is "halfway to a declaration of war" against Japan.

The Senkakus, also claimed by Taiwan, have been a recurring flash point for nationalist antagonism in China and Japan.

A commentary by the official Xinhua news agency Wednesday said Ishihara is purposefully stirring up trouble with China to kindle support at home.

"Observers believe that the motive behind Ishihara's move, taken at a time when the 40th anniversary of the normalization of China-Japan diplomatic ties is drawing near, is to generate publicity and gain political capital in Japan for his hawkish posture," the commentary said. "In other words, Ishihara is attempting to bolster his profile by sabotaging China-Japan ties."

China has indicated it will not hesitate to take any "necessary measures" to safeguard sovereignty over the islands, the commentary added.