More than 3,400 elementary and junior high school students and teachers have contracted food poisoning at 15 schools near Tokyo due to school lunches, local authorities said Thursday.

Students started to complain of food poisoning symptoms such as diarrhea and abdominal pain on June 26 after they ate school lunches including fried chicken and seaweed salad at their schools in Yashio, Saitama Prefecture.

Concluding that the food poisoning was caused by school lunches supplied by lunch deliverer Tobu Kyushoku Center, the prefectural government ordered the company to suspend use of its kitchens for three days.

As the number of students suffering food poisoning increased, 377 students were absent from schools on Monday, though none of them were in serious condition.

E. coli bacteria was detected in the feces of some patients by a local health center.

A local education commission decided to have students in the 15 schools bring their own lunches for the time being, even after the business suspension period of the school lunch deliverer ended.