The concentration of a pesticide residue detected in part of a croquette made by Maruha Nichiro Holdings Inc. subsidiary Aqlifoods Co. in Gunma Prefecture was 2.6 million times higher than the acceptable level, a prefectural official said Tuesday without elaborating on the extent of the health risk.

The Gunma Prefectural Police, who raided the Aqlifoods factory Saturday, suspect someone deliberately poisoned the company’s frozen foods after they were produced, using organic phosphate malathion, a common pesticide but not one used by the firm in its manufacturing process.

The croquette sample was found to have some 26,000 parts per million of the pesticide. The level is also more than double the earlier announced 12,734 ppm for an entire croquette. It is also above the earlier revealed maximum 15,000 ppm found in another type of croquette.

Maruha Nichiro and Gunma-based Aqlifoods detected the highest level of residue in the breaded parts of packaged frozen croquettes distributed in Aichi Prefecture.

The firms included results in a report submitted to Gunma prefectural authorities, while only announcing the lower figure for the whole croquette to the public. The croquette filling contained 4,000 ppm of malathion.

The level of contamination for different parts of other products has not yet been examined. The residue level of an entire product is more important for consumers’ health, the prefectural official said.

The companies earlier said the pesticide found in their products could sicken a child who consumed just one-eighth of a croquette.

The authorities expect the higher level of contamination on the breaded part indicates the pesticide was added after the frozen foods were produced.

“We’re looking into every possibility in our investigation,” a Gunma police spokesman said, declining to be identified and refusing to say if anyone is considered a suspect.

The police began investigating the plant Saturday, he said, adding that several factory employees responsible for the production lines have been questioned.

Consumer reports of foul odors in its products prompted Aqlifoods to launch a probe. It detected malathion in nine frozen food products distributed in six prefectures, including pizzas, croquettes and fried chicken.

Out of 6.4 million products subject to recalls issued from Dec. 29, when Aqlifoods revealed its discovery of the pesticide, the firm had recovered just over 1.1 million products by Saturday.

Masako Mori, state minister for consumer affairs and food safety, told reporters that she will summon senior officials of the companies to the Consumer Affairs Agency on Wednesday to request an improved level of safety.

Mori said the company was too slow in publicizing pertinent information and responding to consumer inquiries.

A tally by Kyodo News showed Monday that more than 200 people in 32 prefectures fell ill after consuming some of the food products sold by Aqlifoods.

Maruha Nichiro said the same day that it has received around 455,000 phone calls from consumers between Dec. 29 and Sunday.

According to data compiled based on information from local governments, at least 50 people suffered vomiting and diarrhea in Gifu, Shizuoka, Aichi and Mie prefectures.

In December alone, 22 consumers in Shizuoka Prefecture claimed to have gotten ill after consuming Torori Kon Kurimu Korokke (Melty Corn Cream Croquettes) or other products subject to the recall. A 5-year-old child and high school students were among those who suffered stomachaches, headaches and vomiting.

Meanwhile, 22 consumers reported feeling ill in the cities of Osaka and Yao in Osaka Prefecture.

A family of four from Settsu, Osaka Prefecture, reported similar symptoms on Dec. 29. The family claimed that the father, his 5-year-old son, 3-year-old daughter and 9-month-old son developed such symptoms within the same day they had consumed croquettes and chicken nuggets.

In Sapporo, two elementary school children who consumed some of the maker’s frozen pastry purchased at a supermarket in the city on Dec. 27 also suffered nausea and diarrhea.

The number of consultations regarding identical symptoms by consumers in Chiba Prefecture reached 26.

Consumers in Shimane Prefecture reported more severe symptoms. The tainted food was blamed for causing three boys and girls to lose consciousness or feel numbness in their hands.

Aqlifoods products also apparently sickened consumers in Aomori, Iwate, Yamanashi, Kagawa and Miyazaki prefectures, as well as in Tokyo and Kyoto.

The Health, Labor and Welfare Ministry will gather health information regarding Aqlifoods products nationwide to update consumers, health minister Norihisa Tamura said at a separate press conference.