The International Olympic Committee (IOC) said on Thursday it was re-introducing testing for gender to determine eligibility to compete in the female category, preventing transgender women from competing.

The screening will mean Olympic women's sports at the 2028 Los Angeles Games will be limited to biological females, which would also rule out those with differences in sexual development (DSD) from competing.

The IOC is abandoning rules it brought in in 2021 which allowed individual federations to decide their own policy and implementing a policy across all 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.

The test will be carried out through a saliva sample, cheek swab or blood sample.

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."

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.

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