Mack Horton says Shayna Jack's positive test for a banned substance has not changed his position on drugs in sport, after earlier refusing to answer questions over the doping scandal engulfing Australian swimming.

Key points: Mack Horton said he was disappointed to learn about Shayna Jack's positive test

Mack Horton said he was disappointed to learn about Shayna Jack's positive test Horton had used the world championships to take a high-profile stand against doping

Horton had used the world championships to take a high-profile stand against doping Swimming Australia chief executive Leigh Russell conceded the saga was "embarrassing" for the sport

Jack revealed on Sunday night she had tested positive for Ligandrol, which forced her to withdraw from the Australian squad for the world titles being held in Gwangju, South Korea.

Horton had used the world championships to take a high-profile stand against doping in sport, refusing to share the podium with Chinese swimmer Sun Yang, who he branded a "drug cheat".

He told the Seven Network the revelation Jack had returned a positive drug test had not shifted his anti-doping stance.

"I was disappointed to learn late yesterday that a fellow Dolphins team member had recently returned a positive A sample," Horton said.

"I applaud the decision to immediately withdraw the athlete in question from further competition until this matter is resolved.

"My position remains firm — clean sport must be a priority for all athletes, all sports and all nations."

Horton had earlier stood in silence when asked if he regretted his stance.

"Just wondering if you had any words about the Shayna Jack dispute?" ABC correspondent Jake Sturmer asked Horton at the world championships.

When asked if he had any words of support for Jack, Horton began to walk away.

'I didn't do this'

Shayna Jack tested positive for Ligandrol, a drug used to treat medical conditions like osteoporosis. ( AAP: Glenn Hunt )

Jack, in a statement linked from her Instagram account, intimated that Ligandrol can be found in contaminated supplements.

"I was in complete shock, asking myself how and why is this happening to me. My brain repeated over and over: 'I have always checked my substances', 'I didn't do this', 'why is this happening to me?', 'I've done nothing wrong'," she said.

"I could still hear the woman in the background on the phone, talking more about what will go on and that I have to leave the camp and return home, as I was placed on immediate provisional suspension until the B sample is tested.

"She also went on to explain what was found in my system, I had never heard of it before, let alone know how to pronounce it; she said it was 'Ligandrol'. I now know that this can be found in contaminated supplements."

American three-time Olympic medallist Ryan Murphy said while the news was "disappointing", he was taking Jack "at her word".

"It's devastating, we had a similar situation a year ago and it's really hard to deal with that because we have relationships with those athletes, we think about the personal side," he said.

"In this case we think about how this affects Shayna, her family and all that.

"We are trying to take her at her word that it wasn't intentionally ingested. Hopefully the process works itself out in the next couple of months when you get all the information."

Swimming Australia admits doping saga is 'embarrassing'

Swimming Australia has come under fire for its handling of the positive dope test by Jack, with claims the sport's governing body tried to cover the news up during the world swimming championships.

News of Jack's test failure broke on Saturday, two weeks after she abruptly left Australian team preparations for the world titles citing "personal reasons".

Mack Horton won gold and silver at the world titles in South Korea. ( AP: Lee Jin-man )

Earlier on Sunday, Swimming Australia chief executive Leigh Russell conceded the doping scandal was "embarrassing" for the sport.

"It is bitterly disappointing, but it also does not change at all Swimming Australia's view of the absolute necessity to have a clean sport and a sport that is drug-free," she said.

"I think that Mack has made a stand for something that he truly believes in. I think we actually have the same stance. We absolutely do not want drugs in our sport.

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

Ms Russell praised Horton for being "passionate" about his anti-doping stance but admitted it was "difficult" to watch last Sunday's medal ceremony, knowing what lay ahead for him and Jack.

"I certainly was watching Mack, distressed about what would befall both Shayna and Mack in the coming days and week," she said.

Australian coach backs Horton

Australia's team coach Jacco Verhaeren said he had supported Horton's podium protest.

"The question is going to be asked 'should he have done that?'," Verhaeren said.

"I think yes because that is a totally different subject as well. This is about someone standing up for clean sport and we still do that.

"If the meet started tomorrow with this knowledge he would stand there again and if I could I would stand next to him."

Mack Horton takes a stand and refuses to share the dais with Chinese swimmer and long time rival, Sun Yang. ( AP: Mark Schiefelbein )

Verhaeren rejected suggestions that Horton had been hung out to dry by the way Jack's case had been communicated.

"Would we all do the same [as Horton]? Probably not. But we don't walk away from it [the discussion] either and particularly not where a fellow teammate, a fellow country member has been found positive," he said.

"I think it is more time than ever to stand up for clean sport."

Former ASADA head Richard Ings took aim at Swimming Australia's decision not to make the drug test public weeks ago, saying: "By covering up and not telling the truth, it makes the story bigger and worse".

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

But Ms Russell insisted Swimming Australia had no choice but to keep the details of the drug test secret until Jack went public.

"Under our policy, it's very, very clear. We must not speak publicly and we have some very strict confidentiality agreements in place so that only ASADA or the athlete are the ones that can actually speak on the particulars of the matter," she said.