XI'AN, March 13 -- Police in Xi'an in northwest China's Shaanxi Province have detained and are investigating three people responsible for allegedly giving antiviral drugs to children to "prevent cold," local government confirmed on Thursday.

The private Fengyun kindergarten's legal representative, surnamed Sun, its principal, surnamed Zhao, and kindergarten doctor, surnamed Huang, are suspected of illegal medical practice, said the press office with the Xi'an municipal government.

Three other responsible people from another kindergarten, named Hongji Xincheng, are also in police custody for further investigation for allegedly giving medicine to children.

Sun is legal representative of both kindergartens. Fengyun kindergarten has 692 kids and Hongji Xincheng has 763.

An initial investigation found that the kindergartens gave some children the prescription medicine moroxydine ABOB to "prevent cold and enhance resistance to improve their attendance" without notifying their parents.

The exact medication dosage and frequency given is still under investigation.

The Xi'an government set up a team with joint efforts by the city's police, education, health, and pharmaceutical supervision authorities after a parent on Sunday said in a microblog that the Fengyun Lanwan Kindergarten had been giving kids the prescription medicine for years.

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

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

They said that the kindergarten administered the drug to ensure the children's attendance, as nursery fees were charged based on the number of days attended.

Parents were anxious to know how large a dose children were given and for how long, as well as the possible harmful side effects and need for follow-up physical examinations.

The investigation team found a receipt for the purchase of 10,000 tablets of the drug from a medicine wholesale company in Xi'an.

The Xi'an municipal government has submitted ten bottles of 1,000 tablets of the medicine found in Fengyun kindergarten for further testing and ordered medical experts to conduct analysis and assessment of the drug's effects on humans.

The government has started free physical examinations for kids in the two kindergartens and arranged professionals to study the inspection results.