South Korea's Park fails doping test

South Korea's Yonhap News quoted Park's Team GMP as saying the positive test had come from an injection given to the swimmer when he was receiving chiropractic treatment two months ahead of last September's Asian Games.

"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," the statement released late on Monday said.

"Park is more shocked by this result than anyone else."

His agency said Park had repeatedly asked if the injection contained illegal substances but was assured it was safe.

The statement did not specify which banned substance Park had tested positive for, nor when the 25-year-old had failed the test.

The swimmer had also passed several doping tests at the Incheon Asian Games, where he won three bronze medals, the statement added.