Australian Swimmer Tests Positive For Banned Substance

Australian swimmer Shayna Jack tested positive to a banned substance prior to the World Swimming Champions.

Many were left confused earlier in the week when Jack mysteriously withdrew from the championships currently being held in Gwangju, South Korea.

At the time, she cited "personal reasons" for her withdrawal.

"It is with great sadness that I have to withdraw from world championships due to personal reasons," Jack said on Instagram.

Shayna Jack. Photo: AAP

Swimming Australia has confirmed Jack was sent home from a training camp in Japan after she had an "adverse test result" during a routine out-of-competition drug test on June 26.

"Once Swimming Australia was made aware of the adverse test result it immediately took action -- in accordance with the national policy -- to provisionally suspend Shayna from the Australian Swim Team while a process was underway and accompanied her back to Australia from a training camp being held in Japan," it said in a statement.

"The Swimming Australia policy also means that any Australian athlete under provisional suspension while ASADA investigations are underway cannot take part in any competition, meaning Shayna was unable to travel to Gwangju to compete at the 2019 World Championships."

It is not known what the substance is.

Jack confirmed the positive test and claimed she did not take the substance knowingly.

"It is with great sadness and heartache that I had to leave due to allegations of having a prohibited substance in my system," she said on Instagram.

"I did NOT take this substance knowingly."

Photo: Instagram/ Shayna Jack

Jack went on to say she would "never" take a banned substance that could jeopardise her career.

"Now there is an ongoing investigation and my team and I are doing everything we can to find out when and how this substance has come into contact with my body," she said.

Jack was slated to compete in the 4x100m and 4x200 freestyle relays, with the Australians favourites to take out the gold.

Australian Mack Horton protests Chinese swimmer Sun Yang. Photo: Getty

Doping has been at the centre of these championships as a number of swimmers, most notably Australian Mack Horton, protest China's Sun Yang competing.

READ MORE: Mack Horton Refuses To Share Podium With Chinese Swimmer

READ MORE: Sun Blows Up After Another Podium Snub By Swimmer

Horton, and later Briton Duncan Scott, have refused to stand on the podium with Sun, after he served a three-month doping ban in 2014.

Sun objected to the out-of-competition test at his Zhejiang home because he questioned the officials' credentials in September last year.

READ MORE: Here's Why People Are Booing Chinese Swimmer Sun Yang

FINA opted not to punish Sun amid claims the testers had not shown adequate identification but the World Anti-Doping Agency lodged an appeal to Court of Arbitration of Sport.

Until the appeal is heard in the Court of Arbitration for Sport, Sun is free to keep competing.