OSAKA -- Police on Friday sent papers to prosecutors on nine officials of Snow Brand Milk Products Co. on suspicion of professional negligence in connection with the massive outbreak of food poisoning that hit western Japan last summer.

The nine include former Snow Brand President Tetsuro Ishikawa, 67, former Senior Managing Director Hiroshi Soma, 62, and Osamu Kubota, 51, former head of the firm's plant in Taiki, Hokkaido, where a bacterial toxin was discovered in samples of powdered skimmed milk produced there.

Police also sent papers on Snow Brand as a corporate body over the food poisoning, which allegedly killed one person and made some 13,400 others sick.

The powdered milk produced in Taiki was an ingredient in dairy products such as low-fat milk and yogurt drinks made at Snow Brand's Osaka plant. The tainted milk resulted in the widespread food poisoning in June and July, experts concluded.

The Osaka plant was shut down in January after 45 years of operation.

Senior officials at both the Taiki and Osaka plants are also suspected of violating the Food Sanitation Law by producing contaminated milk products and filing false reports on production procedures.

It is extremely unusual for police to press professional negligence charges against executives of a major firm. It is also the first case in which a company listed on the first section of the Tokyo Stock Exchange is accused of violating the food law.

According to investigators, Soma was informed about several food-poisoning complaints and about an inspection of the Osaka plant by Osaka municipal health officials on June 28. Osaka also asked him to publish a warning notice in newspapers by midnight June 29.

However, he failed to take any action because the cause of the poisoning was unknown at that time, investigators said.

They allege his inaction led to the death of an 84-year-old woman in Nara Prefecture and some 140 others falling ill.

Ishikawa received information on the food poisoning at around 10 a.m. on June 29, but he was not willing to make the case public, resulting in some 60 others falling ill, investigators said.

Snow Brand held a news conference on the night of June 29 after the city of Osaka publicly stated that three people had been hospitalized after drinking Snow Brand's low-fat milk.

The number of food-poisoning victims had topped 200 by the night of June 29. The company finally ran the notice on the food poisoning in the morning newspapers of June 30.

Snow Brand's executives at the time have admitted they did not take swift measures to stop the spread of the food poisoning because they were concerned about negative effects on the firm's sales.

Kubota is suspected of being responsible for allowing the bacterial toxin enterotoxin A to develop in powdered skimmed milk by failing to take appropriate measures following a power outage on March 31, 2000.

The power outage caused temperature control systems at the Taiki factory to fail, which in turn allowed the staphylococcus aureus bacteria to develop. The enterotoxin was produced by that bacteria, according to a report by Osaka and central government officials.

Ishikawa announced his resignation July 6. On July 12, Snow Brand halted production of milk-related products at all of its 21 milk-processing plants.