Reem Alsalem, the UN's special rapporteur on violence against women and girls, told Sky News she hopes the recommendations will influence the policies of states and sports.

The participation of transgender women or athletes with higher levels of testosterone, in women's events, is one of the most complex and divisive issues in sport.

While LGBT+ advocates urge sport to favour inclusivity, Ms Alsalem is concerned about the physical dangers women in sport can be exposed to if those assigned male at birth are allowed to compete in the same events - notably football.

Ms Alsalem has now submitted a report to the UN that she first revealed to Sky News in August was being prepared amid fears she raised during the Paris Olympics about the dangers of testosterone advantage in women's events.

"Sports have functioned on the universally recognised principle that a separate category for females is needed to ensure equal, fair and safe opportunities in sports," the special rapporteur's report says.

"Multiple studies offer evidence that athletes born male have proven performance advantages in sport throughout their lives, although this is most apparent after puberty.

"Undermining the eligibility criteria for single-sex sports results in unfair, unlawful and extreme forms of discrimination against female athletes on the basis of sex."

The report has a clear recommendation to authorities in sport and at state level.

"In order to ensure safety and fairness in sport at all levels," Ms Alsalem's report says they should "ensure that female categories in organised sport are exclusively accessible to persons whose biological sex is female".

The report continues: "In cases where the sex of an athlete is unknown or uncertain, a dignified, swift, non-invasive and accurate sex screening method (such as a cheek swab) or, where necessary for exceptional reasons, genetic testing should be applied to confirm the athlete's sex."

That follows Ms Alsalem disclosing in our interview in August that sex testing should be reintroduced to the Olympics in the wake of the Imane Khelif issue that overshadowed boxing in Paris.

The Algerian won women's boxing gold amid contentious claims she previously failed a gender eligibility test while insisting she was born a woman.

Details of the testing have not been provided by a boxing governing body whose credibility is disputed by the International Olympic Committee (IOC), which has observer status at the UN, giving it a role in the General Assembly.

Ms Alsalem is due to address the assembly next Tuesday.

She told Sky News: "While there is no obligation to implement the recommendations, the reports drafted by us independent experts of the human rights council carry an authoritative weight.

"We therefore hope that our reports can help state and non-state actors, working on certain policies and that are advocating for change and can also contribute to these important policy conversations, particularly with human rights focused language and arguments since everything has a human rights dimension to it."

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Athletics and cricket are among the global sport governing bodies to prioritise sporting fairness over inclusivity by excluding those assigned male at birth, or who have been through any form of male puberty, from competing in international women's competitions.

But FIFA has a more relaxed position that has been subject to a long-standing review with no timeframe.

In England, the Football Association's policy is that "gender identity should not be a barrier to participation in football" but eligibility is determined on a case-by-case basis.

Players over the age of 16 assigned male at birth wanting to compete in women's football have to show their blood testosterone levels are "within natal female range for an appropriate length of time so as to minimise any potential advantage".

Ms Alsalem's report says "testosterone suppression for genetically male athletes - irrespective of how they identify - will not eliminate the set of comparative performance advantages they have already acquired".

It adds: "To avoid the loss of a fair opportunity, males must not compete in the female categories of sport."

The IOC has said that if your passport says you are a woman you can compete in women's sport.

While the IOC warns against "discriminating on the basis of gender identity or sex variation," its guidelines do accept the "relevance of testosterone to athletic performance will vary from sport to sport".