Radical group raided over bomb attack

Police have raided the Tokyo headquarters of a Japanese ultra-left faction in connection with last week's bomb attack on the office of nationalist history textbook authors.

The group, the Revolutionary Army, claimed in a letter sent to several Japanese media outlets that it planted the bomb.

The group said it was in protest against a school history textbook that has been criticised for whitewashing Japanese atrocities before and during the Second World War.

The group is being investigated on charges of alleged arson in relation to the attack, a Tokyo police spokesman said.

Police believe the group, a faction of the ultra-leftist Revolutionary Workers Association, mailed the letter a day after the attack last Tuesday, Japanese media reported.

The blast at the Tokyo office of the textbook authors and their supporters occurred hours after the city's board of education endorsed the book for use at some prefecture middle schools for disabled students for the next academic year.

Nobody was injured in the attack, but a first-floor window frame was scorched.

The textbook, among the eight approved by the Education Ministry in April, has been criticised at home and abroad for omitting Japanese wartime atrocities, such as germ warfare in China and the 200,000 women forced to work as sex slaves for the Japanese military.