OSAKA — Snow Brand Milk Products Co., whose products have caused an outbreak of food poisoning since late June, replaced a dirty machinery part near a contaminated valve at its Osaka plant before a police inspection last Sunday, police sources said Saturday.

Police have learned that workers at the factory, in Osaka’s Miyakojima Ward, replaced a part connecting a pipe with the contaminated valve immediately before the inspection, the sources said.

The valve was contaminated with at least two types of toxin-producing bacteria, identified as staphylococcus aureus and cereus, and has been pinpointed as the cause of the food poisoning, which had made more than 13,000 consumers of Snow Brand products ill as of Saturday morning.

On Friday, the firm’s tarnished image was dealt another blow when company officials said another product, the Nomu Yoguruto Mainichi Honebuto yogurt drink, produced at the same factory is also contaminated.

The drinks affected, made in late June, come in 1-liter bottles and have expiry dates of July 14, company officials told an evening news conference.

Three brands of milk produced at the factory — Teishibonyu low-fat milk, and Cal-Power and Mainichi Honebuto calcium-enriched milks — have been blamed by health authorities for making more than 13,000 people sick.

Police are questioning factory workers on suspicion they deliberately destroyed evidence important to the food-poisoning inquiry given the timing of the replacement of the valve part. The factory has been closed since last Sunday on the orders of the Osaka Municipal Government.

The original part was still in place when Osaka city’s public health center began inspecting sanitary conditions at the plant on June 28, according to police. However, investigators later discovered that one part was cleaner than the rest of the equipment when they inspected the production line to investigate milk production procedures, they said.

A factory worker has told investigators that the contaminated valve was cleaned only once every three weeks, despite company guidelines requiring that it be washed on a weekly basis, the sources said.

Police suspect the failure to properly clean the valve led to the outbreak of food poisoning.

Snow Brand is recalling all products manufactured at the Osaka plant.

The decision by local governments to refuse to use Snow Brand products was spreading Friday, with the Osaka Prefectural Government announcing that it will not allow products from the Osaka factory to be consumed by students during school lunches for at least two years.

The cities of Ibaraki and Takatsuki, both in Ibaraki Prefecture, also announced Friday that they will not make Snow Brand products available at schools, day-care centers for children or other public facilities for the time being.

Several other municipalities, including Tokyo, and Osaka Prefecture’s Yao, Ikeda and Toyonaka, had earlier decided to stop using Snow Brand products.

The Health and Welfare Ministry is now inspecting hygiene conditions at some 860 Snow Brand factories and other companies that produce dairy products across the nation.

The ministry is expected to announce the results of the inspections around July 20, a ministry official said.

Snow to restructure

OSAKA — Snow Brand Milk Products Co., facing a sharp decline in sales in the wake of the recent outbreak of food poisoning caused by tainted milk, will map out a restructuring plan as early as possible to deal with the incident, a senior company official said late Friday.

Speaking at a press conference, Hiromasa Nakajima, a director in charge of marketing, said the company will first deal with people made ill and pinpoint the cause of the contamination.

Nakajima added that the company plans to update manufacturing facilities to prevent a recurrence of similar incidents and is considering launching a new brand to replace the Snow Brand.

The incident has taken its toll on the company, dragging its stock price sharply lower and forcing Snow Brand President Tetsuro Ishikawa to announce that he will resign at the end of September.

It has also forced the company to pull out of a joint project to launch new coffee drink products under a single brand with Japan Tobacco Inc. and Key Coffee Inc., two of Japan’s leading beverage makers.

Clean bill of health

Inspections carried out by prefectural and municipal governments of Snow Brand Milk Products Co.’s factories nationwide have shown that 18 out of 20 plants met the required health standards, it was learned Saturday.

The faults discovered at the remaining plants, including the lack of cleaning records at Snow Brand’s Hino plant in Tokyo, have already been announced.

The inspections of Snow Brand facilities were carried out on the instructions of the Health and Welfare Ministry between June 3 and 10, after a spate of food poisoning incidents in western Japan was traced back to products from Snow Brand’s Osaka plant, in Mijakojima Ward.

Inspectors were told to examine the production lines of all items made at the respective plants, and check especially thoroughly the parts that need to be cleaned by hand.

As a result, 18 Snow Brand plants were found to be problem-free on such key points as temperature control, cleaning and sanitary management, according to Kyodo News.

While the firm’s Shizuoka plant was also ordered by the city to temporarily suspend use of its production line because there was no record for the mandatory manual washing required by staff, city officials lifted the ban Saturday, saying safety of the products had been confirmed.

However, the Hino plant was ordered by the Tokyo Metropolitan Government to suspend operations because one milk storage tank had no cleaning records.

In Kanagawa Prefecture, Snow Brand’s Atsugi plant was given a verbal warning because a portion of the cleaning process was not being done as stipulated in the company’s manual.