Seven students at a primary school in Southwest China remain in the hospital after they had eaten a free meal provided by the government and got sick, according to a local official.

The rest of the 79 students, who all attend the Babuzhen Central Primary School, in Bijie city's Zhijin county, Guizhou province, have been discharged, according to Chen Guangshi, director of the county's publicity department.

Eighty-six students at the school began to vomit and suffer abdominal pains after they had eaten the free breakfast on March 29.

"Some of the students were vomiting," said Chen. "But no one is seriously ill."

A product made by Mengniu Dairy, a milk producer in China, was involved in the case, which is suspected of causing the food poisoning.

In response to the incident, the county government has sealed up the free meals and taken samples for inspection.

Chen said he suspects the students' illnesses have something to do with the bread, milk and other food served in the breakfasts they ate.

But a report by Bijie's food safety office found the students' sickness had nothing to do with the food's quality. The office instead blamed poor digestion, saying that triggered a psychological reaction among a large group of students and produced the symptoms, China National Radio reported.

In a similar case, also involving Mengniu products, 251 primary school students in Yulin, Shaanxi province, were sent to the hospital in April last year after they had drunk milk distributed by their school and got sick.

Mengniu blamed that case on a psychological reaction and not food quality.

The free breakfast project in Zhijin, or the student nutrition improvement project, is part of the government's pledge to offer free meals to 4,782 rural students from 18 rural elementary schools, Chen said.

The local public security bureau is meanwhile conducting an inspection of the food provider. Further results from that are to be made public soon, Chen said.

Last year, China planned to offer nutritional subsidies to 26 million poor students in rural areas. Many Chinese in the countryside still must contend with a lack of a steady diet, the result in part of poverty and of the long distances they must travel between their homes and schools, which often do not have canteens.

The State Council has extended the project to 680 counties and cities and allocated 16 billion yuan ($2.5 billion) to ensure students receive a daily subsidy of 3 yuan to improve their nutrition.

Rural schools have lately been the sites of several cases of suspected food poisoning.

At about 8:35 am on Friday, 54 students at a primary school in Hujiamiao township in Shaanxi province's Chunhua county, were reported to be vomiting and suffering from abdominal pains after they had eaten breakfast.

An initial investigation found that they had eaten unclean food.

Yang Dongping, a professor at the Beijing Institute of Technology, who has studied educational development in China, said the good intentions that are behind the State Council's project do not ensure it will be carried out properly and that the 16 billion yuan involved in it will be well spent.

Yang said the best way to overcome the project's shortcomings lies in supervision.

Su Jiangyuan in Guizhou contributed to this story.