Australian swimmer Shayna Jack has been notified that she faces a four-year suspension after testing positive to a banned drug, unless she can prove her innocence, a report said Tuesday.

Jack, part of Australia's 4x100m freestyle team that set a world record last year, tested positive to the banned drug Ligandrol, which helps build muscle mass, out of competition late last month.

The Daily Telegraph said the Australian Sports Anti-Doping Authority had told Jack she will receive a four-year suspension, the standard penalty for athletes who test positive for anabolic agents. The 20-year-old will be able to contest the sanction as part of normal processes.

Jack returned home days before the world championships in South Korea, citing "personal reasons". On Sunday she strenuously denied intentionally taking the banned substance, which she intimated could be found in contaminated supplements.

Swimming Australia head coach Jacco Verhaeren, who arrived back in Brisbane from the meet on Tuesday, said he believed Jack could "definitely" bounce back from the doping scandal.

"There are cases where the athlete's name is cleared and it was all a mistake or contamination or whatever it was. And sure they come back from that," he told reporters.

Shayna Jack's manager Phil Stoneman said Monday that the 20-year-old did not ingest the drug via supplement tablets and was now examining her diet.

"It could be meat, it could be mushrooms, it could be anything. It could be something in a bottle," he told national broadcaster ABC.

"It's a bit of jigsaw puzzle as to how this has come into her system."

The Australian team were only told of her positive result on Saturday, with Olympic champion Mack Horton later calling the revelations "disappointing".