Swimming-Australia's Jack admits to positive dope test

The 20-year-old freestyle swimmer, who won two relay silvers and a bronze at the 2017 world championships, made the admission in an Instagram post.

"It is with great sadness and heartache that I had to leave due to allegations of having a prohibited substance in my system," she wrote.

"I did NOT take this substance knowingly. 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 jeopardise my career.

"Now there is an ongoing investigation and my team and I are doing everything we can to find out when and how this substance has come into contact with my body."

The admission will be an embarrassment for Australian swimming with her team mate Mack Horton having played a leading role in the protests against the presence of Sun Yang, who has a doping case pending at the Court of Arbitration for Sport, in Gwangju. (Reporting by Peter Rutherford, writing by Nick Mulvenney, editing by Amlan Chakraborty)