Osaka Prefectural Police will launch a criminal investigation into an outbreak of food poisoning attributed to Snow Brand Milk Products Co. goods on suspicion of professional negligence resulting in bodily injury as well as violations of the Food Hygiene Law, police sources said Wednesday.

Police plan to question Snow Brand executives, and to determine whether there is a causal relationship between contaminated Snow Brand milk products and the food poisoning cases, the sources said. Since late June, more than 14,000 people in 13 prefectures in western Japan have reportedly fallen ill after consuming Snow Brand's low-fat and calcium-enriched milk.

Prime Minister Yoshiro Mori said Wednesday that top executives of Snow Brand are "naturally" responsible for the food-poisoning scandal.