Gender test for Women's 800m winner

South Africa's newly-crowned women's 800 metres world champion Caster Semenya must undergo a gender test, the sport's governing body the IAAF announced on Wednesday.

The 18-year-old has been a revelation this year first domestically, where she vastly improved her times at 800m and 1500m, and also in Berlin on Wednesday where she romped to the title trouncing defending champion Janeth Jepkosgei by over two-and-a-half seconds.

Semenya did not attend a post-race press conference, IAAF secretary general Pierre Weiss took her place.

'I am replacing the winner here tonight. A double investigation is being conducted - one in South Africa, one in Berlin,' said Weiss.

He reiterated that the outcome of the gender test would not be known for some time.

'I am not a doctor, but all the doctors who conducted investigations tell me this sort of thing takes weeks or months,' said Weiss.