The tests carried out on the 18 year-old shortly after her victory in Berlin are believed to have shown that she has a chromosomal abnormality that gives her both male and female characteristics.
According to reports in the Australian media, the medical tests have established that she has no womb or ovaries and that she also has internal testes – the male sexual organs responsible for producing testosterone.
Earlier analysis had revealed that Semenya's testosterone levels were three times the normal level for a woman.
The International Association of Athletics Federations received the results of Semenya's 'gender verification test' this week, but it has refused to confirm the findings until they have been verified by a panel of independent scientific experts and the athlete has been personally informed.
But Pierre Weiss, the IAAF secretary general, hinted strongly at the results on Thursday when he said: "It is clear that she is a woman, but maybe not 100 per cent. We have to see if she has an advantage from her possibly being between two sexes compared to the others."