Caster Semenya will not be able to defend her 800m gold at the IAAF World Championships in Doha in September after a Swiss Court reversed the prior rulings that had temporarily suspended IAAF's regulations regarding testosterone levels in female athletes.

“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,” Semenya said.

A single judge of the Swiss Federal Supreme Court overruled the temporary suspension on Monday, Semenya's representatives said.

The decision means the two-time 800m Olympic champion can no longer compete in events between 400m and the mile as she was allowed to do in June and July during the temporary suspension of the IAAF regulations .

In June, the Swiss court had issued a “super-provisional order,” barring the application of the IAAF rules until a further hearing could take place concerning the rules that were previously approved by the Lausanne-based Court of Arbitration for Sport (CAS).

Semenya will, however, remain "steadfast in her defiance" of the IAAF regulations and will continue to pursue her appeal against the ruling.

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The South African is locked in a bitter dispute with the IAAF over the federation’s rule requiring women with higher than normal male hormone levels, a condition known as hyperandrogenism, to artificially lower their testosterone to compete in races at distances of 400m to the mile.