Tests on South Africa's 800m world champion Caster Semenya are likely to show that she has an inter-gender condition, BBC Sport understands.
Semenya, 18, was asked to take gender tests following her rapid rise to prominence in 2009 and just hours before she won the title in Berlin.
The IAAF has the results but wants them examined before speaking to Semenya.
BBC Sport's Gordon Farquhar said: "It's likely that she has some hermaphroditic or inter-gender condition."
An Australian newspaper has claimed that Semenya is a hermaphrodite - someone who has some or all of the primary sex characteristics of both men and women.
GORDON FARQUHAR'S BLOG
How and who should decide in these cases whether the person be considered a woman or a man?
The reports have sparked an angry reaction in South Africa.
Sports minister Makhenkesi Stofile insisted on Friday: "Caster is a woman, she remains our heroine. We must protect her."
South Africa's athletics president Leonard Chuene told the Star newspaper: "The IAAF told us this week that the tests are inconclusive and they could not give us the results just yet.
"So I really do not know where the Australia media got this latest one from."
National Assembly's sports committee chairman Butana Komphela added: "Someone is guilty of leaking her confidential medical information to Australian newspapers."
But the IAAF's Nick Davies said: "The statements should be treated with caution as they are not official statements by the IAAF.
"We have received the results from Germany, but they now need to be examined by a group of experts and we will not be in a position to speak to the athlete about them for at least a few weeks.
"After that, depending on the results, we will meet privately with the athlete to discuss further action."
The IAAF has confirmed it will not comment further on Semenya until after the IAAF council meeting in Monaco on 20-21 November.
Farquhar added: "We already know that she has testosterone levels that are three times higher than those normally expected in a female.
"It's a serious issue and the athlete has to be told the implications.
"There are three possible outcomes from the expert's discussions: that the condition does not give her a competitive advantage; the condition gives her a competitive advantage, which cannot be treated; or most likely, the condition can be treated in some way if she consents to it, and in time she can return to competition."
"The IAAF has to weigh the interest of the athlete, an apparently innocent victim in this, with its responsibility to ensure fair competition."
Semenya won the 800m title in Berlin in August in the fastest time of the year, one minute, 55.45 seconds, 2.5 seconds ahead of Kenya's 2007 champion Janeth Jepkosgei.