Japan''s Industry Ministry said Wednesday that three more Japanese defense and nuclear contractors have been infected with computer viruses, in addition to Mitsubishi Heavy Industries. The ministry questioned Mitsubishi Heavy Industries and seven other major firms in the defense and nuclear industries starting September 20th, according to Japanese (NHK WORLD) website. The online attacks on Mitsubishi Heavy were made public last month. All the other companies said they have recently received suspicious emails, including some carrying viruses. Three firms said their computers have been infected with viruses, but that they had not yet confirmed whether any sensitive data have been leaked.