Japan has urged China to protect its citizens after thousands of people took to the streets across the country in anti-Japanese protests.
The violence was sparked by a growing feud over ownership of islands in the East China Sea.
Both governments in Beijing and Tokyo are under domestic pressure to take a tough stance over the uninhabited islands. Known as the Senkaku in Japan and the Diaoyu in China, they are surrounded by rich fishing waters.
The latest demonstrations came after 10 Japanese nationalists swam to the islands in a tit-for-tat move following a similar landing by Chinese activists last week.