Any unilateral action taken by Japan on the Diaoyu Island or its neighboring islets is illegal and invalid, Chinese Foreign Ministry spokesman Liu Weimin said on Tuesday.

Liu made the remark when asked to comment on a recent announcement by Tokyo governor Shintaro Ishihara, who stated during a trip to the United States that Tokyo metropolitan government will purchase land on the islands from a private owners this year.

He said any such unilateral action will not change the fact that the Diaoyu Island and its adjacent islets belong to China.

"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 said.