Two-time 800m Olympic champion Caster Semenya has announced her intention to switch to the 200m, with the aim to qualify for the Tokyo 2020 Olympics. 

The 29 year-old South African, who was born with differences in sexual development, is not allowed to compete in athletics events between the 400m and a mile without taking testosterone-reducing drugs.

But the rule under World Athletics does not apply over shorter distances. 

She wrote on Instagram: "My dream has always been, and will continue to be, to compete at the highest level of sport and so in order to pursue my goals and dreams I have decided to change events and compete in the 200m.

"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.

"Thank you to my team who have supported me over the past few months and thank you to all South Africans who believe in me and stand behind me."

In order to qualify for Tokyo 2020 she must run a time of 22.80 seconds. And if she does, she could be a contender against Great Britain's sprint star Dina Asher-Smith, who sealed a gold medal in the 200m at last year's World Championships in Doha.

The three-time world 800m champion was unable to defend her title in Doha after she failed to prevent the governing bodies' rule change. 

The IAAF's conclusion found that without her taking the now-required medication for her DSD, she would have a 'competitive advantage' over other female athletes. 

She added: "I call myself supernatural. I can do anything I want. I always challenge myself. This was not an easy decision to make.

"I am used to running two laps and then you come and run half a lap. You have to adjust, which is not easy, but anything is possible."