The International Olympic Committee on Thursday defended its decision to allow two female boxers to compete at the Paris Olympics despite an ongoing gender row, saying the pair were facing 'aggression' because of an arbitrary decision.

Algerian Imane Khelif, who won her round of 16 welterweight bout over Italian Angela Carini in 46 seconds, and Taiwan's double world champion Lin Yu-ting, who is fighting on Friday, have been cleared to compete in the Olympics.

Khelif's lightning-quick win over the Italian, who decided to pull out after a barrage of punches by the Algerian, piled more pressure on the IOC for allowing them to box in Paris.

Both fighters had been disqualified at the 2023 World Championships after failing International Boxing Association (IBA) eligibility rules that prevent athletes with male XY chromosomes competing in women's events.

But the IBA was stripped of its recognition by the IOC last year over governance and finance issues, with the Olympic body running the boxing competition in Paris.

The IOC said the IBA decision to disqualify the boxers last year was arbitrary and the main cause for the furore that has seen people like British author J. K. Rowling and billionaire Elon Musk voice their opposition to them competing in the Games.

"These two athletes were the victims of a sudden and arbitrary decision by the IBA," the IOC said in a statement. "Towards the end of the IBA World Championships in 2023, they were suddenly disqualified without any due process.

"According to the IBA minutes available on their website, this decision was initially taken solely by the IBA Secretary General and CEO."

Some sports have limited the levels of testosterone allowed for athletes competing in women's competition, while others ban everyone who has been through male puberty.

Differences of Sexual Disorder (DSD) are a group of rare conditions involving genes, hormones and reproductive organs. Some people with DSDs are raised as female but have XY sex chromosomes and blood testosterone levels in the male range.

The IOC said the rules of eligibility were based on those of the Tokyo Games in 2021 and cannot be changed during a competition.

"The current aggression against these two athletes is based entirely on this arbitrary decision, which was taken without any proper procedure – especially considering that these athletes had been competing in top-level competition for many years," the IOC said.

"The IOC is saddened by the abuse that the two athletes are currently receiving," it added. "Every person has the right to practice sport without discrimination."