OSAKA — Health authorities have announced that 1,524 people have complained of illness in Osaka and seven other prefectures in western Japan after drinking low-fat milk products produced by Snow Brand Milk Products Co.

Officials of a medical laboratory in Wakayama said in the afternoon that they detected a gene linked to the toxin present in yellow staphyloccus in leftover milk that the victims had drunk.

The officials added, however, that they are not yet able to determine whether it was the cause of the food poisoning outbreak, since staphyloccus itself is occasionally found in milk.

The victims, ranging in age from 10 months to 90, suffered diarrhea, stomach pain and vomiting after drinking the milk and products made from it, the authorities said Friday.

The milk, packaged in 1-liter and 500-ml cartons, was produced on June 23 and 24 at the company’s factory in Osaka’s Miyakojima Ward.

During that two-day period, 128,000 cartons were produced, each with a shelf life of one week, Snow Brand officials said.

Snow Brand announced Thursday that it has halted low-fat milk production at the Miyakojima plant and said about 298,000 cartons of low-fat milk shipped after last Friday were being recalled.

Company officials said virtually all affected milk products have been removed from stores, but conceded that a large quantity has already been sold.

Osaka city health officials and Snow Brand acknowledged they were aware of the poisoning outbreak 10 p.m. Wednesday, but failed to reach a decision on a recall until 12 hours later.

It was not until Thursday afternoon that company officials decided to announce the poisoning, as “the president and managing director were traveling by plane and could not be contacted,” officials said.

On Friday, the number of reported cases of food poisoning soared in Osaka Prefecture to 922, with another 230 cases in Wakayama Prefecture, including a 1-year-old toddler.

The other poisoning cases were reported in Hyogo, Nara, Kyoto, Shiga, Okayama and Hiroshima prefectures.

Although in most cases, reported symptoms were light, in Wakayama, five children were hospitalized, and two of them — a 7-year-old and a 11-year-old boy — remained hospitalized as of Friday noon.

Osaka health officials conducted tests on milk samples left by a family of five who reported symptoms Tuesday, but have so far been unable to locate bacteria that are normally associated with food poisoning.

But because the staphylococcus bacillus sometimes retains toxins even after pasteurization, Osaka officials scheduled its third inspection of the Osaka factory Friday for further studies.

Three Health and Welfare Ministry officials were also set to arrive to help ascertain the cause of the poisoning.

According to Wakayama Prefecture officials, no arsenic, cyanide, cadmium or 66 other toxic metals were found in the milk.

On Friday, about 100 Snow Brand employees visited the hospitals and homes of consumers who became ill, and the firm fielded over 110 phoned-in complaints.

At a kindergarten in Wakayama Prefecture, 15 children who ate ice cream made from the milk felt sick but were not seriously affected, authorities said.

Osaka Municipal Board of Education officials said that on Friday, nine elementary schools and one high school had 5,200 milk bottles for lunch delivered from Snow Brand’s Kobe factory instead of the Osaka factory, officials said.

The Osaka Prefectural Board of Education is also instructing schools to use milk packaged other than at the Osaka factory.

Snow Brand officials said the company has not received any extortion threats.

The Osaka Prefectural Government has set up a special task force on the food-poisoning outbreak and will keep 29 health centers in the prefecture open over the weekend to deal with any new victims. The health centers will be open between 9 a.m. and 5:45 p.m.

The prefectural government also replaced some 27,000 bottles of 200-ml milk that had been delivered from the Miyakojima factory to 56 public schools in the prefecture for Friday’s lunch with products from the firm’s Kobe plant, although the milk was not the low-fat type.

The officials said they took the measure as a precaution, adding that they will ask Morinaga Milk Industry Co. to supply milk to those schools from its local plant.

Authorities are calling on the public not to drink Snow Brand’s low-fat milk but take the products to nearby health centers.