SEOUL (AFP) - Disgraced South Korean swim star Park Tae Hwan took legal steps on Thursday in his dogged campaign to overturn a doping-related ban on participating in the Olympic Games in Rio.

The multiple Olympic medallist completed an 18-month drug suspension in April after testing positive for an anabolic steroid in out-of-competition controls before the 2014 Asian Games.

But he remains barred from competing in Rio de Janeiro under a Korean Olympic Committee (KOC) rule which prohibits athletes from representing South Korea for three years after the expiration of any doping ban.

Park insists the rule is unfair and has appealed to the Court of Arbitration for Sport (CAS) in Lausanne, which is now considering his case.

On Thursday, his legal team sought an injunction from the Seoul Eastern District Court that would make any eventual CAS ruling binding on the KOC.

"The court action is aimed at securing the binding power of the CAS ruling," lawyer Lim Sung Woo told journalists.

There was no immediate reaction from the KOC, which last week turned down Park's request to have the additional three-year national team suspension lifted.

He has repeatedly begged for a chance to compete in what would be his third, and probably last, Olympics - at one point getting down on his hands and knees during a press conference.

The 26-year-old was once the poster boy of South Korean swimming - courted by advertisers and idolised by fans.

He won 400m freestyle gold and 200m freestyle silver at the 2008 Beijing Olympics, and two silver medals at the 2012 London Olympics, as well as 400m world titles in 2007 and 2011.

On his competitive return to the pool last month, he easily won the 100m, 200m, 400m and 1,500m freestyle events at the 88th Dong-A meet, which doubles as a national trial.

His positive doping test was only revealed in January last year, and was initially blamed by Park's management team on the incompetence of a doctor at the hospital where the swimmer was receiving treatment.