MELBOURNE — Swimming Australia on Sunday defended their concealment of Shayna Jack's positive doping test while one of her team mates was conducting a public campaign against China's Sun Yang at the world championships.

Jack was withdrawn from the Australia squad ahead of the championships in Gwangju with the swimmer and Swimming Australia (SA) initially saying it was for personal reasons.

The 20-year-old freestyle swimmer, however, revealed on Saturday that she had tested positive for a banned substance in an out-of-competition test on June 26.

Jack, who denies wittingly taking a banned substance, on Sunday said her 'B' sample had confirmed the presence in her sample of Ligandrol, an anabolic agent. She faces a four-year ban.

Accusations of hypocrisy were immediately levelled at Australia with the non-disclosure of the positive test set against Mack Horton's condemnation of Sun, who served a drug ban in 2014 and is embroiled in another doping controversy.

Chief executive Leigh Russell said on Sunday, however, that SA had been bound by confidentiality while an investigation was conducted by the Australian Sports Anti-Doping Authority (ASADA).

"An Australian swimmer returning a positive result is both bitterly disappointing and embarrassing to our team, our sport and our country," Russell told reporters in Melbourne on Sunday.

"The ASADA agreement requires Swimming Australia to maintain confidentiality until such time as either ASADA or the individual athlete release details of an adverse result.

"I accept this is a frustrating position but I also accept that Shayna has a right to a fair process."

Former ASADA chief Richard Ings had said earlier that rules did allowed sports to identify athletes who had adverse test results.

"When an athlete is provisionally suspended, the rules do allow the sport to make a public announcement," he told the Australian Broadcasting Corporation.

"Ultimately, what was said by Shayna Jack and Swimming Australia weeks ago about vague personal reasons become transparent weeks later as a lie."

ASADA later released a statement backing Russell's stance.

Russell said Jack should enjoy presumption of innocence until the process was completed but if she was found guilty SA would "enforce any sanction imposed".

Horton had earlier sparked a firestorm at the championships when he refused to acknowledge Olympic champion Sun, who he has previously declaimed as a "drug cheat", during the 400m freestyle medal ceremony.

The Chinese multiple world champion is competing under the shadow of a World Anti-Doping Agency (WADA) appeal against governing body FINA's decision to clear the 27-year-old of wrongdoing during the random drug test last September.

Russell said SA shared Rio Olympic champion Morton's opinion on doping in sport and suggested that an earlier disclosure of Jack's failed test would not have changed his position.

"Mack is making a stand for something he believes in and I think we have the same stance," she said. "We absolutely do not want drugs in our sport.

"I think that Mack made a stance he was comfortable with, and he would be comfortable with that today."

SA were also criticized for not having a member of the management or coaching staff face reporters in Gwangju when the news broke on Saturday, leaving world and Olympic champion Cate Campbell to represent the team.

"That was my call, in retrospect, we could have done that differently," Russell said.

Jack, who won two silvers and two bronzes in relays at the last world championships, on Sunday posted a lengthy explanation of the whole affair on social media and vowed to clear her name.

"Deep down, I feel I shouldn't have to defend my reputation as I know that I didn't do this," she wrote.

"Why would I put myself through this anguish and risk jeopardizing my career and my character? I did not and would not cheat and will continue to fight to clear my name." — Reuters