LAUSANNE, March 23 (Xinhua) -- South Korea's swimming Olympic champion Park Tae-hwan was banned for 18 months by world swimming body FINA on Monday for failing a dope test in last September.

The 25-year-old, a four-time Olympic swimming medallist, tested positive for a banned anabolic steroid at an out-of-competition control before the Asian Games.

The ban for his first doping violation will run until March 2, 2016 which rules him out of this year's world championships in Kazan, Russia from July 17 to August 2, but should allow him to compete at the Rio Olympics.

All Park's results after September 3, 2014, have also been cancelled which means handing back his three bronze medals, which he won at last year's Asian Games in Incheon, South Korea.

Park -- who has six Asian Games titles to his name -- won 400m freestyle gold and 200m freestyle silver at the Beijing 2008 Olympics, becoming South Korea's first Olympic swimming medallist.

He also won silver in both events at the 2012 London Olympics, along with 400m gold in the world championships in 2007 and 2011.