LAUSANNE, Switzerland - A doping case involving Chinese swimmer Sun Yang is going to the Court of Arbitration for Sport.

CAS says the World Anti-Doping Agency has appealed against a decision by swimming's governing body to only give the three-time Olympic champion a warning in a case involving the destruction of a doping control sample.

CAS has not set a date for the hearing.

British newspaper the Sunday Times reported incidents involving Sun when a doping control official visited his home in China last September. A vial of Sun's blood was reportedly smashed with a hammer, and his entourage disputed the official's credentials.

The 27-year-old Sun served a three-month ban in 2014 for testing positive for a substance then classed as a stimulant. Sun would face a more severe sanction for a second offence, including a possible ban from the Tokyo Olympics.