Eighty-six primary school students have been affected by a suspected food poisoning incident in east China's Shandong Province, said local authorities Thursday.

The children struck by food poisoning were under medical observation in a hospital.

As of Thursday morning, 10 children were still under medical observation in a hospital in Shenxian County, while others had been discharged, said a county government spokesperson.

The children, all from the county's Mingtian Primary School, began showing symptoms of acute gastroenteritis after eating lunch on Wednesday, said the spokesperson.

He said samples of the school's food were being examined and the government has ordered inspections for all of the school dining halls in the county.

During the past week, three similar suspected food poisoning incidents have affected more than 70 children in two primary schools in northern China's Hebei Province and a kindergarten in the country's eastern Jiangxi Province.

Additionally, 135 students became ill after drinking contaminated water at Zhangjiying Middle School in Hebei's Longhua County.