SYDNEY - Australian swimmer Shayna Jack has revealed that the banned substance which ruled her out of the 2019 World Aquatic Championships in South Korea was a drug called Ligandrol.

Known to increase muscle growth and strengthen bone, the 20-year-old freestyler said in a statement posted to social media on Sunday evening, that substance found in her body was the result of a contaminated supplement or product.

"I did not and would not cheat," Jack said.

"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.'"

"On Friday the 19th of July my B sample results were in. I had felt a sense of hope knowing I didn't take this substance and that it was all a mistake during the testing and that I could return to compete for my country and with the team, however, that wasn't the case."

Citing the incident as a major "embarrassment" to Australian swimming's governing body, Swimming Australia chief executive Leigh Russell told reporters yesterday "the adverse findings were both bitterly disappointing and embarrassing to our team, our sport and our country."

Critical of the decision to keep the failed test a secret after it was originally stated that Jack would not join the national team in Gwangju due to "personal reasons," former Australian Sports Anti-Doping Authority (ASADA) chief executive Richard Ings posted to social media "we now know this was an untruth," he said.

"The real reason, known at the time of this announcement, was she had been provisionally suspended for a positive A sample drug test. Athletes need to be frank from day one."

But according to Russell, Swimming Australia could not legally disclose the results of the adverse drug test at that time.

"Athletes in these situations have a right to a process. That process is continuing and that is now between ASADA and our athlete."

With Jack potentially facing a lengthy ban from athletic competition, it could be some months before a punishment is handed down.