Controversial Chinese swimmer Sun Yang will get a public hearing by the Court of Arbitration for Sport (CAS) over an appeal brought by the World Anti-Doping Agency (WADA) against him and the Federation Internationale De Natation Association (FINA) which claimed Sun did not violate doping regulations after an out-of-competition test last year.

The open hearing by the Court of Arbitration for Sport will probably be in Switzerland but is "unlikely to be before the end of October," the court said on its website Tuesday, and "will be open to the public (including the media)."

The court did not reveal the exact date and gave no detail of which party asked to postpone the process. It was previously reported to be scheduled in September.

Public trial is not common in the court's history as Sun will be only following another three-time Olympic swimming champion, Michelle Smith de Bruin of Ireland, as the only athlete opting not to have a closed-door hearing in the court's 35-year history.

Smith de Bruin challenged a four-year ban imposed by FINA in 1998 two years after the Atlanta Olympics for allegedly tampering with a urine sample by adding alcohol.

A panel of three CAS judges heard the case over two days in May 1999 in its home city Lausanne, Switzerland, and upheld the original verdict.

Details of evidence in the previously confidential court process were published on the eve of the world championships held last month in South Korea.

Swimmers from Australia, Britain, and the United States objected to Sun being allowed to compete in Gwangju while the appeal case was pending. After Sun won the 200 and 400 meters freestyle events, medalists from Australia and Britain made silent protests at the podium.

The first male Olympic swimming champion of the country won two gold medals at the 2012 London Olympics and one in Rio de Janeiro four years later. He could be banned from the Tokyo Games next year because of incidents at his home in China last September.

A collection team sent to take blood and urine sample failed to complete its work in an escalating late-night dispute.

Sun disputed an official's credentials, and a vial of blood handed over to his entourage was destroyed with a hammer.

WADA challenged swimming body FINA's verdict in January that a warning was enough for Sun, who served a three-month ban in 2014 for a positive test.

The CAS hearing should be the first in public since the European Court of Human Rights last year said athletes should have more rights to open the sports court to scrutiny.