FINA's decision has already sparked change at Global Association of International Sports Federations observer member International Rugby League (IRL), which has banned transgender players from women's competitions until further notice.

Football's global governing body FIFA has confirmed that a review is being conducted on the participation of transgender players.

"FIFA is currently reviewing its gender eligibility regulations in consultation with expert stakeholders," a spokesperson told Reuters.

"Due to the ongoing nature of the process, FIFA is not in a position to comment on specifics of proposed amendments to the existing regulations."

The spokesperson added: "Should FIFA be asked to verify the eligibility of a player before the new regulations will be in place, any such case will be dealt with on a case-by-case basis, taking into account FIFA's clear commitment to respect human rights."

FIFA added that it is taking guidance from medical, legal, scientific, performance and human rights experts, and taking into account the position of the International Olympic Committee (IOC).

One of women's football's biggest stars, Megan Rapinoe, a London 2012 Olympic gold medallist and back-to-back FIFA Women's World Cup winner with the United States, has told Time magazine that she believes banning transgender women from competing in elite sports is "cruel" and "disgusting" following FINA's decision.

Rapinoe is a high-profile advocate for several LGBTQ+ organisations.

On the other side of the debate, World Athletics' President Sebastian Coe told The Times in March that be believes "the integrity of women's sport if we don't get this right, and actually the future of women's sport, is very fragile", following the success of American transgender swimmer Lia Thomas.

Thomas became the first openly transgender athlete to win a National Collegiate Athletic Association Division I title when she triumphed in the women's 500 yards freestyle representing the University of Pennsylvania.

Heated disagreements following her victory provided the backdrop for FINA's decision at its Extraordinary Congress here on Sunday (June 19).

Reacting to FINA's move, Coe told the BBC that he welcomed the development, and said that World Athletics would review its policies by the end of the year.

"We see an international federation asserting its primacy in setting rules, regulations and policies that are in the best interest of its sport," the two-time Olympic gold medallist said.

"This is as it should be.

"We have always believed that biology trumps gender and we will continue to review our regulations in line with this.

"We will follow the science.

"We continue to study, research and contribute to the growing body of evidence that testosterone is a key determinant in performance, and have scheduled a discussion on our regulations with our council at the end of the year."

Coe added: "When push comes to shove, if it's a judgement between inclusion and fairness, we will always fall down on the side of fairness - that for me is non-negotiable."

World Athletics rules capping athletes' testosterone levels at five nanomoles per litre in some women's running events came into force in 2019.

The requirements controversially led to Namibia's Christine Mboma and Beatrice Masilingi being forced to miss the women's 400 metres at the Tokyo 2020 Olympics, after an assessment found that the pair have differences in sexual development and high natural levels of testosterone.

Changes have already been implemented at a non-Olympic governing body, with the IRL banning transgender players from women's international matches pending further research.

"Until further research is completed to enable the IRL to implement a formal transgender inclusion policy, male-to-female (trans women) players are unable to play in sanctioned women's international rugby league matches," it said.

Association of Summer Olympic International Federations member World Rugby, which governs rugby union, had already banned transgender players from playing in women's international matches.

On Sunday, the FINA Extraordinary Congress approved with approximately 71.5 per cent of the votes to change its policy on the eligibility of transgender athletes in women's aquatics events.

Individuals are now required to have completed transition by the age of 12 to compete in women's competitions, effectively banning transgender women if they have gone through any part of the process of male puberty.

FINA President Husain Al-Musallam also announced that the governing body hopes to create an "open category", claiming that this would ensure "that everybody has the opportunity to compete at an elite level".

In November last year, the IOC approved a new framework for transgender and differences in sexual development athletes which recommends more flexibility to International Federations.

This marked a move away from the 2015 consensus statement, which had a "one-size-fits-all" approach to the participation of transgender athletes, requiring those seeking to compete in the female category to lower their testosterone to below 10 nanomoles per litre for at least 12 months.

New Zealand's weightlifter Laurel Hubbard became the first openly transgender woman to compete at an Olympic Games at Tokyo 2020.

Last week, the International Cycling Union updated its rules on transgender athletes' participation, increasing the transition period on low testosterone to two years and lowering the maximum permitted plasma testosterone level.