A police car outside the Tongxing kindergarten in Shanghai on Tuesday.?

A male staff member of a kindergarten in Minhang district has been detained on suspicion of sexually violating five girls, Minhang police said on Tuesday.

Police said they received reports on June 16 from two parents that their daughters had been violated at the Shanghai Minhang district's Tongxing kindergarten.

Police investigated the case immediately and decided that a 35-year-old male staff member, surnamed Han, was a suspect. They detained Han later that day.

Police have been visiting students and parents since June 16 to further investigate the case.

Han might have sexually violated the girls when they took an afternoon sleep, according to investigators' initial findings.

The kindergarten is a privately run preschool. Its monthly charge is about 400 yuan ($62). Currently more than 200 students attend the school.

Parents said the kindergarten has been running for more than a year. However, approval for planning and constructing the kindergarten by Minhang education bureau was dated Dec 28, 2010, according to a file published on the Minhang district government's website.

The registered fund of the kindergarten is 400,000 yuan and the entire investment is 800,000 yuan. The purpose of the kindergarten is to educate migrant workers' children aged from three to six, according to the file.

Han, the suspect, is a cousin of one of the kindergarten's supervisors, Shanghai Television reported.

A girl told her parents that a man at the kindergarten had been constantly "touching" her for more than a year, and the parents later found similar cases at the kindergarten and called the police, said a parent who spoke on condition of anonymity, reported xinmin.net, a Shanghai news website.

The kindergarten was still operating normally on Tuesday, according to xinmin.net.

A clerk with Minhang education bureau, who spoke on condition of anonymity, told China Daily on Tuesday afternoon that the bureau was aware of the case, and discussions about the case were to be held on Tuesday and Wednesday mornings, but he declined to make any comment before police have concluded their investigation.

The police are still looking into the case, according to the district police bureau.

This case draws attention to the quality of privately run kindergartens, which have been encouraged to open in Shanghai to satisfy demand for preschool education for the increasing number of migrants workers' children.

Earlier reports said the number of migrant workers' children in Shanghai who are of preschool age would increase to 200,000 by 2012 from the current 80,000.

To increase resources for preschool education and seek ways to accommodate these migrant children, the Shanghai education commission announced last year that it plans to build more than 400 kindergartens within five years.

These kindergartens will be built mainly in migrant population areas, such as Baoshan district, Minhang district and Pudong New Area.

"The government should increase supervision for these private kindergartens," said Gao Shuang, a teacher at a public kindergarten in the city.

"Meanwhile, a comprehensive training and assessment system should be set up for the kindergartens' staff members to ensure the healthy growth of children."

A local resident, surnamed Xie, whose son will enter kindergarten next year, said: "While setting up more kindergartens in the city, under no circumstances should authorities neglect the quality of instruction at these preschools, especially privately run ones.

"Unlike public kindergartens, teachers, facilities and education standards at private kindergartens are still cause for concern," Xie said.