Police on Tuesday raided several Kyowa Perfumery & Chemical Co. locations, including its headquarters in Tokyo and a factory in Ibaraki Prefecture, for allegedly producing and shipping banned flavoring agents.

Kyowa Perfumery distributed the substances to more than 175 food companies in 44 prefectures, sparking a nationwide recall of foods containing the chemicals.

Police have also been questioning company executives on a voluntary basis. Company President Akio Hirase, 55, has admitted he overlooked the company's use of the banned agents despite finding out in summer 2000 that doing so was illegal.

The flavoring agents were made at Kyowa's factory in Juo, Ibaraki Prefecture, using banned substances, including acetaldehyde, propionaldehyde and castor oil, since 1992 when it received a license to produce the flavoring agents and other products, according to Ibaraki prefectural health authorities.