CANBERRA, July 27 -- Australian swimmer Shayna Jack has been notified of an adverse test result by the Australian Sports Anti-Doping Authority (ASADA), confirmed Swimming Australia on Saturday.

According to a statement on the official Swimming Australia website, the test was conducted by ASADA on June 26, and Jack was "provisionally" suspended from the Australian swimming team and returned to Australia from a training camp being held in Japan.

Jack won a gold medal last year in the Gold Coast Commonwealth Games as part of the world record-breaking 4x100 women's freestyle team.

The Australian newspaper reported that the 20-year-old swimmer "mysteriously withdrew from the world championships" earlier this month citing "personal reasons".

"Officials initially failed to elaborate on the circumstances behind her exit," said The Australian. But the incident was revealed by a local media outlet on Saturday, which said that cause of the swimmer's withdrawal was due to "an abnormal A sample during routine, pre-competition testing".

The Australian quoted Jack as saying that she didn't "knowingly" take a banned substance.

"Swimming has been my passion since I was 10 years old and I would never intentionally take a banned substance that would disrespect my sport and jeopardize my career," she was quoted as saying.

In an official statement, Swimming Australia CEO Leigh Russell said: "As you would expect, we are bitterly disappointed with allegations a swimmer has a prohibited substance in her system, although it is important to point out that the matter is yet to be determined. We will continue to provide appropriate support for Shayna. We will also provide support for our team members who are still in Korea, and our team and our organization will continue to reaffirm our zero tolerance approach."

In its report, The Australian called the issue "an absolute disaster", after Australian swimmer Mack Horton courted controversy at the ongoing FINA World Championships in Gwangju, South Korea by snubbing China's Sun Yang on the podium, labelling him a "drug cheat".

Australian swimmers were kept in the dark about Jack's test result, the newspaper said. "It raises the question of whether Horton would have made his spectacularly public stand had he known a team-mate had just tested positive. He now must be feeling incredibly let down by his Australian team management."

Fellow Australian outlet 9News said in its report that "Australian swimmers have led the charge in criticizing drug cheats and tonight's bombshell may target them as hypocrites."