Paris - Caster Semenya will not defend her world 800m title in Doha in September after a Swiss judge overruled a temporary suspension on the IAAF's controversial testosterone-curbing rules, her representatives said on Tuesday.
The ruling means the 28-year-old can no longer compete in events between the 400m and mile, as she did in June and July. The World Championships are scheduled between September 28-October 6 in the Qatari capital.
"I am very disappointed to be kept from defending my hard-earned title, but this will not deter me from continuing my fight for the human rights of all of the female athletes concerned," said the South African who is also a two-time Olympic gold medallist.
Semenya's representatives said in a statement that, on Monday, "a single judge of the Swiss Federal Supreme Court reversed prior rulings that had temporarily suspended the IAAF regulations pending the outcome of Caster's appeal against the CAS award".
"In this latest decision, the Supreme Court emphasised the strict requirements and high thresholds for the interim suspension of CAS awards and found that these were not fulfilled."
Dorothee Schramm, the lawyer leading Semenya's appeal, added that the judge had made a "procedural decision" that has no impact on the appeal itself.
"We will continue to pursue Caster's appeal and fight for her fundamental human rights. A race is always decided at the finish line."
Semenya is locked in a bitter dispute with the International Association of Athletics Federations (IAAF), which should be settled by a final ruling from Switzerland's supreme court on Semenya's appeal against the regulations.
The IAAF released a brief, non-committal, statement on Tuesday evening.
"We understand the Swiss Federal Tribunal will be issuing its full decision on this order tomorrow and the IAAF will comment once the tribunal makes its reasoning public," it said.
Semenya is classified as a woman, was raised as a woman and races as a woman.
But for the IAAF, women like Semenya, with certain masculine attributes due to differences of sexual development (DSD), are classified, biologically, as men. It is a position hotly contested by South African officials.
The IAAF, seeking "to ensure fair competition for all women", argues that DSD athletes, like Semenya, born with the "46 XY" chromosome rather than the XX chromosome most females have, would have an advantage in all events based on their levels of testosterone that are in the male range.
"Caster Semenya remains steadfast in her defiance of the highly controversial IAAF regulations that require female athletes with naturally elevated testosterone levels to undergo hormonal drug intervention in order to compete in international competitions," the athlete's representatives said.