(This March 21 story corrects distance range to 400 metres to 1 mile, not 400 to 1,000 metres.)
LONDON (Reuters) - The Court of Arbitration for Sport (CAS) said on Thursday it would postpone its decision on Caster Semenya's appeal hearing against the International Association of Athletics Federations (IAAF) until the end of April.
South African 800-metres double Olympic champion Semenya is seeking to overturn a new set of IAAF regulations that are aimed at lowering the testosterone levels of hyperandrogenic athletes.
The IAAF contend that Semenya and other female athletes that are classed as having differences in sexual development (DSDs) gain an unfair advantage due to their higher testosterone levels, but only in races between 400 metres and 1 mile.
Under its new rules, athletes classed as having DSDs must reduce their blood testosterone level to below five (5) nmol/L for a continuous period of six months before they can compete. They must then maintain it below that level continuously.
CAS have called the hearing "one of the most pivotal CAS cases" that could have a wide reaching consequence not just for the future of athletics, but sport in general.
The body had been expected to announce its decision on March 26, six months prior to the World Championships in Doha.
It said on Thursday that since the Feb. 18-22 hearing, the parties have filed additional submissions and materials. No specific date for the decision has been set.
The IAAF said that, given the delay, it would alter the six-month rule for the world championships in Qatar in September and introduce a "special transitional period" so that affected athletes could still compete.
"The IAAF has decided that the delay should not prejudice the affected athletes," it said in a statement.
It added that, assuming its new regulations were upheld, affected athletes who comply with the new limit from one week after the final CAS decision until the start of the world championships in September would be allowed to take part.
(Reporting by: Ossian Shine; Editing by Toby Davis and Christian Radnedge)