Plans by the International Olympic Committee to introduce stricter guidelines for transgender athletes before the Tokyo 2020 Games have run into the sand because its panel of scientists is struggling to reach agreement on such a thorny issue.

The scientists had been expected to recommend halving the permitted testosterone levels for trans women competing in elite sport. However, several sources have confirmed to the Guardian that the IOC’s draft guidelines have been parked, for now, because the whole subject is so politically charged and sensitive.

Under the current IOC guidelines, issued in November 2015, athletes who transition from male to female can compete in the women’s category without requiring surgery to remove their testes provided their total testosterone level in serum is kept below 10 nanomoles per litre for at least 12 months.

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Those guidelines, used by most sports federations to draw up their transgender policies, have proved controversial, given that women’s testosterone levels tend to range between 0.12 and 1.79 nmol/l, while men’s are typically between 7.7 to 29.4 nmol/l.

The Guardian understands some scientists on the IOC panel have argued that reducing the permitted testosterone levels to 5nmol/L – below most males – would provide a reasonable compromise between inclusion and fairness, ensuring that trans women could still compete in the women’s category while taking away most of the advantages of undergoing male puberty.

However, others disagree, pointing to the emerging findings from the Karolinska Institute in Sweden, which show that testosterone suppression for transgender women has little effect on reducing muscle strength even after a year of treatment. That indicates that at least some of the physical advantages of those who have gone through male puberty are maintained even after transitioning.

One source told the Guardian that the draft IOC proposals “had gone around the houses” without getting anywhere and that it was unlikely that a new consensus position would be reached before the Tokyo Olympics.

Another said they were more hopeful but acknowledged that reaching an agreement had “proved far more difficult than expected because this is such a tricky political and emotive issue”.

The Guardian understands there will be meetings between now and Tokyo with the intention of getting individual sporting federations to create their own policies on transgender athletes. However, many governing bodies are reluctant to do anything without the IOC taking the lead in such a controversial area.

Several high-profile athletes, including Martina Navratilova, Kelly Holmes and Paula Radcliffe, have also spoken out about the potential damage to women’s sports by allowing trans women to compete when they are potentially bigger, stronger and faster having gone through male puberty. The British swimmer Sharron Davies, a silver medallist at the 1980 Olympics, put it earlier this year: “I believe there is a fundamental difference between the binary sex you are born with and the gender you may identify as.

“To protect women’s sport, those with a male sex advantage should not be able to compete in women’s sport.”

Others, though, maintain that sport must strive to be as inclusive as possible and that, as things stand, there are very few trans women at the elite level. The transgender academic Joanna Harper has argued: “Transgender women after hormone therapy are taller, bigger and stronger on average than cisgender women. But that does not necessarily make it unfair. In high levels of sport transgender women are substantially under-represented. That indicates that, whatever physical advantages transgender women have – and they certainly exist – they are not nearly as large as the sociological disadvantages.”

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Just about the only thing all sides agree on is the need for more scientific research. Many sports are wary about how best to respond to the issue. Last year Hannah Mouncey, a former member of the Australian men’s handball team, was blocked from playing in Australian rules football’s professional women’s league on the grounds of strength and physique.

However, Laurel Hubbard, a New Zealand weightlifter who competed in men’s competition before transitioning at the age of 35, was allowed to take part in the 2018 Commonwealth Games and recent Asian games, where she won the overall gold in the 90+kg category.