AP

South Africa's Caster Semenya celebrates winning gold in the woman's 800m final at Carrara Stadium during the Commonwealth Games on the Gold Coast.

The IAAF is set to reveal a new rule which is expected to greatly effect middle-distance star Caster Semenya.

The Daily Mail has reported that the world governing body for athletics will implement a move to limit naturally-produced testosterone for women in track races from 400 metres to the mile.

The controversial rule change for athletes with hyperandrogenism is expected to force Semenya either to take medication to reduce her testosterone levels, or change to longer-distance events, the Mail said.

The 27-year-old South African won Olympic gold in the women's 800m in London 2012 and Rio 2016 and recently easily triumphed in the 800m and 1500m at the Commonwealth Games in Australia.

READ MORE: Semenya notches Games double 

A similar rule on hyperandrogenism was intoduced by the IAAF in 2011  but in July 2015 the Court of Arbitration for Sport suspended the regulations after an appeal by the Indian government on behalf of their sprinter, Dutee Chand, the Mail reported.

The IAAF president, Lord Coe, said last month the organisation wanted to protect the rights of female athletes.

"It is clear that this is one of the toughest subjects the council and I have been discussing,' he said.

"This is about our responsibility to ensure, in simple terms, a level playing field. It is our sport and it is up to us to decide the rules."

 - Stuff