Public health authorities in Aomori Prefecture have banned Yoshidaya, a local maker of bento meals, from operating due to food poisoning cases caused by its products.

As many as 270 people in 21 prefectures in the country have become sick after eating bento meals supplied by Yoshidaya, based in the Aomori city of Hachinohe. The company voluntarily suspended operations starting Sunday.

The number of patients could increase, a Hachinohe public health official said Saturday.

Staphylococcus aureus and Bacillus cereus, which cause food poisoning, were detected in the feces of the patients who ate Yoshidaya meals as well as unopened products made by the company, according to Hachinohe public health officials.

Yoshidaya President Hiroki Yoshida said in a statement that the company believes the bacteria grew due to insufficient handling when it purchased rice from a supplier outside Aomori.

"It's solely our responsibility. We're very sorry for betraying customer trust. We'll make every effort to apologize and compensate for the damage," Yoshida said.

The food poisoning was caused by 12 types of bento meals sold across the country for two days from Sept. 16. The first case was reported by public health authorities in Fukushima Prefecture on Sunday.