Rio de Janeiro: The Chinese Swimming Association has confirmed Chinese swimmer Chen Xinyi has failed a doping test at the Rio Olympics.

Chen, who came fourth in the women's 100m butterfly final, tested positive for hydrochlorothiazide (HCTZ) on Sunday, a diuretic banned for its potential to mask the use of other performance-enhancing drugs.

The association said the 18-year-old had now supplied her "B" sample for further testing and requested an evidentiary hearing, according to the official Xinhua news agency.

The revelation was headline news on China's major internet news sites and was met widely with shock on Chinese social media, with Chen Xinyi the top-searched item on China's Twitter-like Weibo on Friday afternoon. "If this is true, what I want to know is who made you take the drugs?" one comment read.