Caster Semenya's birth certificate clearly states she is female
The BBC has seen the birth certificate of South African athlete Caster Semenya, which states that the new 800m world champion is female.
Ms Semanya, 18, has been told to take a gender test after several remarkable improvements in recent performances.
The case has provoked an angry reaction in South Africa, where many have said she has been unfairly treated.
A South African official said Ms Semenya almost snubbed her gold medal ceremony because of the test.
Visited by the BBC, Ms Semenya's mother told the BBC that the 18-year-old athlete is certainly female.
Dorcus Semenya: "It's my girl... I gave birth to that girl"
"I have no doubt about what I see. It's a girl," Dorcus Semenya said.
South Africa's ruling African National Congress, along with numerous officials and other bodies, has said the athlete has been unfairly treated.
The president of Athletics South Africa, Leonard Chuene, told a local newspaper that he had to "persuade" the athlete to go to the podium to accept her award.
"She is not rejoicing. She [didn't] want the medal," Mr Chuene told South Africa's Times newspaper.
"She told me: 'No-one ever said I was not a girl but here [at the World Athletics Championships in Berlin] I am not. I am not a boy.'
"Why did you bring me here? You should have left me in my village at home," Ms Semenya reportedly asked Mr Chuene.
On Thursday Mr Chuene expressed outrage at the order that Ms Semenya undergo a gender verification test.
He said she had been "humiliated" and treated like a "leper".
The International Association of Athletics Federation ordered Ms Semenya to take the test after she improved her personal best by more than eight seconds over the past year.
The IAAF stresses that it does not suspect her of deliberately cheating but questions whether she may have a rare medical condition which gives her an unfair advantage.
IAAF officials have said Ms Semenya would not necessarily have her medal withdrawn if she "failed" the tests.
In South Africa the ANC has urged people to rally round "our golden girl", while the Young Communist League of South Africa said she had been the victim of racism.
Groups supporting her have been formed on social networking site Facebook.