Lausanne (AFP) - The International Olympic Committee said on Thursday only “biological females” will be allowed to compete in women’s events, preventing transgender women from competing.

The IOC is re-introducing testing for gender to determine eligibility to take part in women’s events from the 2028 Los Angeles Olympics onwards.

The move will also rule out many athletes with differences in sexual development (DSD).

In a major shift of policy, the IOC is abandoning rules it brought in in 2021 which allowed individual federations to decide their own policy and is instead implementing a policy across all Olympic sports.

“Eligibility for any female category event at the Olympic Games or any other IOC event, including individual and team sports, is now limited to biological females, determined on the basis of a one-time SRY gene screening,” the IOC said in a statement.

They will be carried out through a saliva sample, cheek swab or blood sample. It will be done once in an athlete’s lifetime.

IOC president Kirsty Coventry said: “The policy we have announced is based on science and has been led by medical experts.

“At the Olympic Games even the smallest margins can be the difference between victory and defeat.

“So it is absolutely clear that it would not be fair for biological males to compete in the female category. In addition, in some sports it would simply not be safe.”

In a press conference later, Coventry added: “I do feel that this policy is a policy that is supporting equality and fairness and the protection of the safety on the field of play.”

- Removes potential Trump clash -

The new policy removes a potential source of conflict between the IOC and US President Donald Trump as the Los Angeles Olympics comes onto the horizon.

Trump issued an executive order banning transgender athletes from women’s sport soon after he came to office.

The US leader later took credit for the IOC’s new policy in a post on his Truth Social network later Thursday.

“Congratulations to the International Olympic Committee on their decision to ban Men from Women’s Sports,” Trump wrote. “This is only happening because of my powerful Executive Order, standing up for Women and Girls!”

While sports such as swimming, athletics, cycling and rowing have brought in bans, many others have permitted transgender women to compete in the female category if they lowered their testosterone levels, normally through taking a course of drugs.

World Athletics welcomed the change of tack.

“We have led the way in protecting women’s sport over the last decade,” said a spokesperson for track and field’s international body.

“Attracting and retaining more girls and women into sport requires a fair and level playing field where there is no biological glass ceiling.

“This means that gender cannot trump biology. A consistent approach across all sport has to be a good thing.”

Gender testing was first introduced at the 1968 Olympics and last used at the 1996 Atlanta Games but then scrapped after criticism from the scientific community.

The new policy is set to face some opposition too, especially in relation to athletes with DSD, the rare condition in which a person’s hormones, genes and reproductive organs may have a combination of male and female characteristics.

The British Journal of Sports Medicine said in an article this month there was “no scientific data of acceptable quality regarding sport performance advantage of people with DSDs possessing an SRY gene.”

It added: “Evidence regarding their athletic performance is extremely limited and problematic.”

The best-known DSD athlete of recent years is South African runner Caster Semenya, the two-time Olympic women’s 800m champion who has male XY chromosomes.

The IOC is bringing in the new policy after the women’s boxing competition at the 2024 Paris Olympics was rocked by a gender row involving Algerian fighter Imane Khelif and Lin Yu-ting of Taiwan.

Khelif and Lin were excluded from the International Boxing Association’s 2023 world championships after the IBA said they had failed eligibility tests.

However, the IOC allowed them both to compete at the Paris Games, saying they had been victims of “a sudden and arbitrary decision by the IBA”.

Both boxers went on to win gold medals.

Lin has since been cleared to compete in the female category at events run by World Boxing, the body that will oversee the sport at the 2028 Los Angeles Olympics.