TIANJIN, China — The Chinese government accused Japan on Tuesday of stealing a group of disputed islands in the East China Sea after the Japanese government announced that it had bought them for nearly $30 million.
In a show of strength, China dispatched two maritime law enforcement ships to the islands, known as the Diaoyu islands in China and as the Senkaku in Japan.
The ships are commonly deployed in the South China Sea where China and its neighbors have other territorial disputes over islands.
Xinhua, the Chinese state news agency, said Tuesday that the marine agency had drafted an ‘‘action plan’’ for asserting China’s claim to the islands.
The Japanese government’s purchase of the islands from their private owners, a Japanese family, was intended to prevent the conservative governor of Tokyo from buying them, a step that would have heightened the clash with China further, Japanese officials said. The Tokyo governor, Shintaro Ishihara, had said he would develop the islands, something the national government does not plan to do.
But in an unusual array of strong statements by top leaders in recent days, China has asserted that the islands in the East China Sea have belonged to China since ancient times.
The Chinese president, Hu Jintao, warned the Japanese prime minister, Yoshihiko Noda, at a summit meeting in Russia over the weekend that buying the islands would be illegal, Xinhua reported.