Melbourne: Australian swimmer Shayna Jack tested positive for a banned substance forcing her withdrawal before the world championships.
She was suspended from the Australian team and sent home from its pre-worlds training camp in Japan.
"I did NOT take this substance knowingly", she wrote on Instagram.
"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."
Jack said that she and her team are doing everything they can to find out when and how the substance entered her body.
The 20-year-old swimmer initially cited personal reasons for her sudden withdrawal from worlds, and Swimming Australia had declined to elaborate.
Swimming Australia CEO Leigh Russell said that the governing body is bitterly disappointed about the positive test but will continue to support Jack.
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