Olympic swimming gold medallist Park Tae-hwan has been left "shocked" by a positive doping test, which his agency has attributed to an injection given to the South Korean swim star during chiropractic treatment ahead of last year's Asian Games.
Park won the 400 metres freestyle crown at the 2008 Beijing Games and is a two-time world champion.
His clean-cut image and poster-boy looks have made him one of the most popular athletes in South Korea, where he is known affectionately as 'Marine Boy'.
However, that image looks to have been tarnished by a failed test, which the Korea Swimming Federation said was administered by the sport's world governing body FINA, South Korea's Yonhap News reported on Tuesday.
The swimmer was notified of the failed test in December, it added.
Park's agency, Team GMP, said the swimmer had repeatedly asked if the injection contained illegal substances but had been assured it was safe.
"As a world class swimmer, Park Tae-hwan has been extremely careful about what he takes, and he hasn't even taken cold medicine so that he wouldn't fail doping tests," Yonhap quoted the statement as saying.
"Park is more shocked by this result than anyone else."
Park's agency said it would soon hold a media conference to discuss the issue.
It did not specify which banned substance Park had tested positive for, nor when the 25-year-old had failed the test, but it said the swimmer had passed several doping tests at the Sept. 19-Oct. 4 Incheon Asian Games.
The news comes months after Park's great rival, China's Sun Yang, was also found to have failed a doping test.
Sun, winner of two gold medals at the 2012 London Olympics, served a three-month suspension last year after testing positive for the banned stimulant trimetazidine during the national swimming championships in May.
The China Anti-Doping Agency (CHINADA) could have imposed a longer ban but said it decided on three months because Sun had been given medication, normally used to combat angina, by a doctor to treat a heart issue and was unaware it had been added to WADA's banned list this year.
News of Sun's suspension did not break until after the Asian Games, where he competed against Park.