South African middle distance athlete Caster Semenya is aiming to run in the 200 meters at the 2020 Tokyo Olympics, as the 29-year-old is prohibited from defending her 800 meters Olympics title because she refuses to adhere to testosterone regulations set by governing body World Athletics. 

Semenya is a double Olympic gold medalist in the 800 meters, but as an athlete with differences in sexual development (DSD) is bound by regulations limiting normal levels of testosterone in competitors racing in events ranging from 400 meters to a mile. 

"My dream has always been, and will continue to be, to compete at the highest level of sport," Semenya said in a statement on Friday. 

"This decision has not been an easy one but, as always, I look forward to the challenge and will work hard, doing all I can to qualify for Tokyo and compete to the best of my ability for South Africa," she added. 

She must clock a 22.80-second 200 meters to qualify for Tokyo but she is some way off the qualifying time as her best time achieved Friday in Pretoria when winning a provincial championships final was 23.49 sec. 

Semenya is appealing to the Swiss Federal Tribunal against a Court of Arbitration for Sport ruling that supported regulations introduced by the sport's governing body, World Athletics. 

A ruling is expected in the first half of this year, which could take her close to the July 24 start of the Olympics. 

(With input from agencies)