Sydney, Jul 29 (AFP) The coach of drug-tainted Australian swimmer Shayna Jack says he will stand by her, insisting she is a clean athlete and will be cleared of wrongdoing.

The 20-year-old, part of Australia's 4x100m freestyle team that set a world record last year, tested positive to Ligandrol, which helps build muscle mass, out of competition late last month.

But it only came to light at the weekend, in a huge embarrassment for Australian swimming after Olympic champion Mack Horton's high-profile protest against Chinese rival Sun Yang at the world championships in South Korea.

Horton refused to share a podium with Sun, who is accused of smashing vials of blood following a test last year and Jack's coach Dean Boxall, who also mentors 400m world champion Ariarne Titmus, said he knew of her test result before the championships, but anti-doping regulations prevented him speaking out earlier.

She returned home days before the event started, citing "personal reasons", and on Sunday strenuously denied intentionally taking the substance, which can be found in contaminated supplements.

"I've been in contact with her all the time. The girl is devastated. I'm devastated. I love my athletes," Boxall told the Sydney Morning Herald on Monday.

"I support Shayna, I support Swimming Australia and I certainly support our stance on zero tolerance for drug cheating. So does Shayna. That's why she left immediately. We followed the process."

He added that "we are going to fight with her and Swimming Australia is going to fight with her".

"I believe strongly her story. I know my athlete. This is a very, very sad story. We've got to go through the process and respect it and we trust it. I believe it will all be finished (Jack will be cleared). Absolutely."

Swimming Australia chief executive Leigh Russell on Sunday called the test result "bitterly disappointing and embarrassing".

In his first comments on Jack, Horton told Australian media in South Korea he was "disappointed".

"I applaud the decision to immediately withdraw the athlete in question from further competition until this matter is resolved," he said. "My position remains firm -- clean sport must be a priority for all athletes, all sports and all nations."

The Australian team, including Horton, was only told of her positive result on Saturday. AFP SSC

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