The Chinese Swimming Association says Chen Xinyi has become the first swimmer to test positive for banned substances at the Rio Olympics.
The announcement was reported early Friday by Xinhua, the official state news agency.
The 18-year-old Chen finished fourth in the women's 100-meter butterfly Sunday, missing a bronze medal by nine-hundredths of a second.
She was also scheduled for compete in the 50m freestyle beginning Friday.
There was no immediate details on the positive test, which come on the heels of seven Russian swimmers being allowed to compete in Rio after initially being banned because a huge, state-sponsored doping operation in their homeland. That decision sparked vocal complaints from several swimmers, most notably American Lilly King.
Also, Australian gold medalist Mack Horton feuded with Sun Yang over the Chinese star's three-month suspension for using a banned stimulant in 2014.
