XI'AN, March 13 -- The legal representative of two kindergartens in northwest China's Shaanxi Province has been arrested for "illegal medical practice" after parents disclosed the schools have long been administering antiviral drugs to pupils.

Along with the legal representative, who is surnamed Sun, the principal and the doctor of Fengyun Lanwan Kindergarten were also arrested on the same charges, a joint investigation team with Xi'an government authorities confirmed with Xinhua on Thursday.

Police have also taken the principal, vice principal and the doctor of another kindergarten, Hongji Xincheng, into custody. Sun is also the legal representative of Hongji Xincheng.

The suspects told police the kindergartens had been giving kids of some classes the prescription medicine moroxydine ABOB for years, because they believe it can prevent the kids from catching cold and develop their immunity to disease so as to ensure the children's attendance.

They also admitted they did so without notifying parents.

The case was first exposed by a parent in a microblog on Sunday. According to the parent, nursery fees were charged based on the number of days attended.

Dozens of parents on Tuesday gathered and blocked the road in front of Fengyun Lanwan Kindergarten demanding an explanation.

Some parents told Xinhua their kids were experiencing discomfort with several symptoms, including dizziness, leg pain and stomachaches.

They are eager to know how large a dose pupils were given and for how long, as well as the possible harmful side effects and need for follow-up physical examinations.

The Xi'an City government has set up a joint investigation team comprising members of the city's police, education, health and pharmaceutical supervision authorities.

It confirmed that the kindergartens have given kids prescription medicine that may cause adverse reactions of sweating, loss of appetite and hypoglycemia.

The actions are unlikely to cause accumulated harmful effects as the amount given to most of the children has not exceeded the specified dose. However, the dose given to the lower class was slightly excessive.

The Xi'an municipal government has submitted the medicine for further testing and ordered medical experts to conduct analysis and assessment of the drug's effects on humans.

The government will also offer free physical examinations for kids with symptoms.