Algerian boxer Imane Khelif's 46-second win at the Paris Olympics on Thursday sparked a furious row about gender eligibility rules, with public figures from around the world weighing in on the controversy.

Italian boxer Angela Carini retired hurt and shrugged off attempts by Khelif to shake her hand, before collapsing to her knees and sobbing uncontrollably in the middle of the ring.

Khelif advanced to the quarter-finals of the women's 66kg category after unloading two strong punches to the face of Carini, who had blood on her shorts and was unable to carry on because of a badly hurt nose.

"My nose started dripping (with blood) from the first hit," said the distressed Carini, who also broke down in tears when talking to reporters.

The 25-year-old sobbed: "I fought very often in the national team. I train with my brother. I've always fought against men, but I felt too much pain today."

Khelif and Taiwan's Lin Yu-ting, who fights on Friday at 57kg, were disqualified from the 2023 world championships in New Delhi run by the International Boxing Association (IBA) but deemed eligible to box in the women's competition in Paris.

Both boxers also competed at the Tokyo Olympics three years ago.

The IBA, in a statement on Wednesday, said Lin and Khelif were disqualified from the world championships as "a result of their failure to meet the eligibility criteria for participating in the women's competition".

"The athletes did not undergo a testosterone examination but were subject to a separate and recognised test, whereby the specifics remain confidential," it added.

The International Olympic Committee is running the boxing in the French capital because of governance, financial and ethical issues at the IBA.

IOC spokesman Mark Adams told reporters this week that they "are women in their passports and it's stated in there that they are female".

The IOC reiterated the same line as the furore raged following the easy win for Khelif, who will return to the ring on Saturday.

The IOC accused the IBA of making "an arbitrary decision", adding: "The current aggression against these two athletes is based entirely on this arbitrary decision."

But the one-sided bout sparked an immediate reaction from Italian Prime Minister Giorgia Meloni, who said the fight was "not on an equal footing" and she did not agree with the IOC's policy.

"I think that athletes who have male genetic characteristics should not be admitted to women's competitions," she said during a meeting with Italian athletes in Paris.

- 'Forever tarnished' -
Donald Trump declared on his Truth Social network: "I WILL KEEP MEN OUT OF WOMEN'S SPORTS!"

Harry Potter author JK Rowling said on X that the Paris Games would be "forever tarnished by the brutal injustice done to Carini".

The writer has incurred the wrath of activists in recent years over her stance that biological sex is immutable, often in relation to the transgender debate.

"A young female boxer has just had everything she's worked and trained for snatched away because you allowed a male to get in the ring with her," she said.

Also on social media, tennis great Martina Navratilova described the situation as "deplorable", alleging that Khelif was a "biological man".

Reem Alsalem, the UN special rapporteur on violence against women and girls, wrote on X that Carini "and other female athletes should not have been exposed to this physical and psychological violence based on their sex".

- 'Lies' -
Khelif was given a huge roar when she came into the North Paris Arena, partly from members of the large Algerian diaspora in the French capital.

Before and during the brief bout they chanted her name, but the action itself was over in a flash.

Khelif stopped only briefly to talk to reporters afterwards, saying: "It's always satisfying to win in such an important competition, but I remain focused on my goal of a medal."

Algeria and Taiwan sprang to the defence of their boxers.

Taiwan President Lai Ching-te gave the 28-year-old Lin his public backing, saying on Facebook "we should stand united and cheer for her".

Algeria's Olympic Committee (COA) condemned what it called "malicious and unethical attacks directed against our distinguished athlete, Imane Khelif, by certain foreign media".

The COA hit out at "lies" that were "completely unfair".