Trans female athletes must lower their testosterone levels further in order to partake in women's competitions.

The new ruling means a 50 per cent reduction, with competitors now required to keep their testosterone levels below five nanomoles per litre of blood rather than ten.

The ruling by the IAAF council in Doha approved the 'Eligibility Regulations for Transgender Athletes' which will replace the former 'Sex Reassignment Regulations (2012)'. 

Under the new regulations a transgender female athlete does not have to be recognised by law in her new gender but must provide a signed declaration that her gender identity is female.

The new ruling is the same as that which applies to athletes with differences of sexual development (DSD), as in the case of South Africa's Caster Semenya. 

The 28-year-old has been fighting against IAAF rulings since she was banned from competing in any distance between 400m and 1500m without testosterone-reducing medication. This includes the defence of her 800m Olympic title.

She must be able to demonstrate that the testosterone levels in her blood have been below five nm/litre of blood for at least 12 months before being able to be eligible to compete. They must also be able to maintain this level.

The issue continues to stir debate among competitors, spectators and commentators. Ex-Olympians Sharron Davies and Daley Thompson have both spoken of their concerns that allowing trans females to compete in women's sport will have a damaging impact. 

Davies claimed that women's sport was now being used as a "live experiment" and Daley said the inclusion of transgender athletes "has the potential to put an end to women's sport."