Police in Japan have set up a special team to investigate tampering with official government websites by computer hackers.

As the Japanese government held an emergency meeting to discuss computer security the hackers broke into an official website for the third time in three days.

One of the messages they left in Chinese criticised the Japanese government for refusing to acknowledge the seriousness of the Nanking massacre in 1937, when Japanese troops killed thousands of Chinese civilians. Over the weekend, China criticised a conference organised by right-wing nationalists in Japan which said reports of the massacre had been greatly exaggerated. Another Japanese government Internet site was altered so it linked directly to pornographic web page.

From the newsroom of the BBC World Service