Japan Today reported Tuesday Maruha Nichiro Inc. was recalling 6.3 million packs of frozen food products after customers returned them to stores complaining of a foul smell.
Police were considering the possibility the pesticide malathion had been introduced into the products intentionally, the newspaper said.
Japan Today said there have been no reports of illness among consumers linked to the tainted products, but Maruha Nichiro executives have apologized for the problems, which have been traced to frozen foods produced by the Aqli Food Corp. plant in Oizumi, Gunma prefecture.
Aqli Food Corp. is a Maruha Nichiro subsidiary.
Health officials inspected the plant Monday. At a news conference, company executives said they had yet to figure out how malathion got into their product line.