The SCEG said that its findings after an 18-month investigation proved that the current approach to the inclusion of trans athletes in sport "requires a reset and fresh thinking."

"The inclusion of transgender people into female sport cannot be balanced regarding transgender inclusion, fairness and safety in gender-affected sport where there is meaningful competition," the report read.

"This is due to retained differences in strength, stamina and physique between the average woman compared with the average transgender woman or non-binary person assigned male at birth, with or without testosterone suppression."

However, it also insisted that a holistic policy covering all sports would not be possible, urging national governing bodies and sport governing bodies to consider how the SCEG's recommendations could be implemented specifically to their competitions.

The report included 10 guiding principles.

Sport England, Sport Scotland, Sport Northern Ireland, Sport Wales and UK Sport all feature in the SCEG, and insisted that they are committed to including transgender people in sport.

Evidence gathered suggested it is "fair and safe for transgender people to be included within the male category in most sports," but that "competitive fairness cannot be reconciled with self-identification into the female category in gender-affected sport."

Testosterone suppression was covered in the report, but it was found that it is "unlikely to guarantee fairness between transgender women and natal females."

The International Olympic Committee (IOC) allows transgender athletes to compete in women's competitions if their testosterone levels are under the 10 nanomoles per litre limit for at least 12 months.

However, the SCEG said this is "unlikely to result in the achievable minimisation of physical capacity."

The report said that a "case-by-case" judgement would be "unlikely to be practical nor verifiable," and that "categorisation by sex is lawful."

It claimed governing bodies needed to decide whether their top priority is inclusion, fairness or safety, and use this to inform their policies.

The SCEG offered three options for consideration.

The first was the option of prioritising the inclusion of transgender people into the sport's existing sex categories, which it recommended for sports that have "determined that inclusion rather than fairness is the objective of the category."

For such sports, it recommended that a five nanomoles per litre limit rather than the IOC's 10 would be more suitable for including transgender women, non-binary or gender fluid people recorded male at birth in its female categories.

An alternative approach suggested was running a "female" and "open" competition, with competitors in the former having to declare themselves as recorded female at birth and the latter open to anyone.

The third possibility was additional competitions including "universal admission" being created which are not dependent on sex or gender, which could lead to adaptations such as non-contact versions of team sports, the introduction of handicaps or the use of non-traditional formats or distances.

The Sports Councils vowed to work with national and sport governing bodies to determine a course of action.

A mixed reaction came out of the report from campaigners.

As per the BBC, Dr Nicola Williams of Fair Play For Women welcomed the SCEG's findings.

"It is now increasingly recognised that the existing approach to transgender inclusion in sport is out of date and no longer fit for purpose," Williams said.

"We commend the Sports Councils for taking the lead to address this difficult and sensitive issue.

"This comprehensive review confirms what we all know: sex matters in sport.

"That's why we have always needed a separate protected category for females and still do.

"It's good to see all the UK's sports councils confirming that reserving a sport category for biological females is both lawful and necessary to guarantee the fair and safe inclusion of women in sport.

"This guidance puts an end to the idea that it is possible to allow people, who were born male into the female sports category, without women and girls paying the price."

However, the charity Mermaids was more critical.

"We are disappointed to read this review, which rather than focussing on bettering its existing guidance for trans people in sport, yet again ignores the lived experiences of trans people, and misinterprets the Equality Act and academic literature," a statement read.

"This report will have ramifications for trans people in the sporting community, and only seeks to cause unnecessary hostility, exclusion and confusion for those wishing to participate in sport.

"It is important to remember that the SCEG report only exists as guidance: it is not mandatory.

"Sports groups and organisations are entitled and encouraged to write and implement their own policies on including trans and non-binary people in sport."

The charity Stonewall added through Twitter  the guidance "makes some harmful assumptions."

"It assumes that there is an inherent conflict between inclusion, fairness and safety," it added.

"In reality, the three go hand in hand."

The Tokyo 2020 Olympic Games saw New Zealand's Laurel Hubbard become the first openly trans woman to feature at the event in the women's over-87 kilogram weightlifting competition.

The IOC medical and scientific director Richard Budgett admitted in July that current guidelines including the 10 nanomoles per litre testosterone limit are no longer fit for purpose.

However, it was confirmed last month that an update would be delayed until after the Beijing 2022 Winter Olympics due to "very conflicting opinions."

International Federations have been encouraged to devise their own regulations.

In 2019, World Athletics required transgender athletes to be less than five nanomoles per litre to take part in its events.

World Rugby in 2020 concluded that transgender women should not play women's contact rugby as it could lead to injuries due to "physiological differences," although some National Associations including Canada Rugby expressed opposition.