Seoul: South Korea's Olympic committee upheld its decision on Thursday to ban former Olympic swimming champion Park Tae-hwan from competing at the Rio Games even though he finished an 18-month doping suspension in March. The South Korean Olympic Committee reiterated that it will not change its rules that block athletes from the national team for an additional three years after the end of their doping suspensions, reports Xinhua. Park's legal team said they would ask the Court of Arbitration for Sport (CAS) to immediately start an arbitration process after the Korean Olympic Committee rejected the swimmer's appeal. "And if the KOC fails to respond to a decision by the CAS, we would file a lawsuit in South Korean court," Park's lawyers said in a statement. Lee & Ko, a Seoul-based law firm representing Park, said the CAS will be able to reach a decision by early July, before the July 18 entry deadline for swimmers at the Rio Games. The 26-year-old Park came off an 18-month ban in March after testing positive for testosterone in an out-of-competition doping test. He won 400m freestyle gold and 200m freestyle silver at the 2008 Beijing Olympics, and two silver medals at the 2012 London Olympics. He is the only South Korean to win an Olympic medal in swimming.