A group of ultra-nationalist Chinese hackers said they attacked a series of Japanese websites in retaliation for a visit by Japan's prime minister to a controversial war memorial.
The announcement by the Red Hacker's Alliance came one day after Japanese Premier Mr Junichiro Koizumi visited the Yasukuni Shrine, which honours nearly 2.5 million war dead.
"When news of this issue broke, some members of the Red Hacker's Alliance were summoned to discuss a reaction," the group said in an e-mail posted on the Sina.com website.
"Eventually we decided to do what we are good at to express the online youth's extreme dissatisfaction with the new Japanese government," the group said.
The list of hacked Japanese targets included sites run by companies and research institutes as well as a fire-fighting site, the alliance said in its statement.
Visitors to one of the affected Japanese sites today were met by a white screen and the triumphant words "hacked by sharpwinner".
China's hacker community has emerged as an increasingly aggressive actor during the regular flare-ups over emotional issues that mark China's ties with countries such as the United States and Japan.
In early May, local hackers claimed to have attacked over 1,000 US websites in a "cyber-war" triggered by the standoff over the US spy plane stuck on southern Hainan island after a mid-air collision with a Chinese jet. AFP