Parents of at least 10 toddlers in Beijing have made accusations of child abuse against RYB Education Kindergarten, a well-known chain of preschools, Beijing News reported on Thursday.

Police in Chaoyang district are investigating claims that children at the company's Xintiandi branch had needle marks on their bodies and were repeatedly fed unidentified white pills.

Employees at the preschool said the principal is cooperating with the investigation so is unable to take questions from media, according to the report.

Parents gathered at the gates of the kindergarten at noon on Thursday and demanded a thorough probe of the allegations. Police have yet to release a statement on the case.

RYB Education Kindergarten was China's largest early years education service provider in terms of annual revenue last year, according to the Frost & Sullivan Report.

The company, which is listed on the New York Stock Exchange, operates 80 kindergartens directly and has 175 franchises in 130 cities and towns, according to the RYB prospectus.