(REUTERS) - Former Olympic champion Park Tae Hwan was left off South Korea's national swimming team on Wednesday due to a controversial Korean Olympic Committee (KOC) regulation that tacked three years onto his 18-month doping ban imposed by world governing body Fina.

Park completed the Fina ban in March after testing positive for testosterone ahead of the Incheon Asian Games in September 2014 but under KOC regulations he must wait three years from the end of his ban to be eligible for national selection again.

Critics of the regulation say it punishes an athlete twice for the same offence and there have been suggestions the swimmer could take his case to the Court of Arbitration for Sport (CAS).

Park, who won gold in the 400m freestyle at the 2008 Beijing Games to become the first Korean to win an Olympic swimming medal, won all four of his races and met Olympic qualification standards at recent national trials.

However, his name was not on the Korea Swimming Federation's preliminary list of athletes who will have a shot at making the squad for the Rio Olympics.

Park's coach, Roh Min Sang, said the KOC's stance defied belief.

"I cannot understand it at all," he told Reuters by telephone on Wednesday.

Roh said experts had told him at a discussion session on Tuesday that in the event of an unresolved issue between the KOC and the International Olympic Committee, the KOC must give way according to the its own articles.

"The doping suspension is already over and the fact that they still did this is ... incomprehensible," he fumed.

Roh added that he would do his best to get Park reinstated and said the swimmer was still training hard.

Park's management agency, Team GMP, said Park has requested a meeting with the KOC before he decides on his next move.