World Rugby could ban transgender athletes from playing women's rugby because of safety concerns.
It would be the first international sports federation to prohibit transgender women from competing.
World Rugby said it had undertaken a review of its "rugby-specific transgender guidelines" in light of the "latest peer reviewed research".
It said it was committed to "ensuring a safe and inclusive playing environment at all levels of the game".
In a statement to BBC Sport, it added: "The latest peer reviewed research confirms that a reduction of testosterone does not lead to a proportionate reduction in mass, muscle mass, strength or power. These important determinants of injury risk and performance remain significantly elevated after testosterone suppression.
Photo: World Rugby
"This presents a clear safety risk when transgender women play women's contact rugby and this position is reflected within draft guidelines that are currently out for stakeholder consultation prior to the World Rugby Council considering the matter later this year.
"Rugby is an inclusive and welcoming sport and World Rugby is fully committed to continuing to work with relevant groups to explore appropriate participation pathways for transgender athletes and is funding further research into the safe participation of all players in rugby. This is in addition to extensive non-contact participation avenues that are available to everyone at union level."
A decision is expected to be made when unions vote on the proposals at a World Rugby Council meeting in November.
The possible ban was first reported in the Guardian which has seen World Rugby's leaked 38-page draft document.
A World Rugby transgender workshop in February sought a "comprehensive review" for the sport, bringing together experts from across the globe to look at a "rugby-specific framework for all, prioritising athlete welfare, inclusion and fairness".
One of the experts to attend the workshop was Dr Nicola Williams, director of women's rights advocacy group Fair Play for Women, who described World Rugby's position as "trailblazing" if it goes ahead with the decision.
"The sensitivity around this issue around transgender issues, and the fear that people would be called transphobic for raising concerns has meant that most sporting bodies have buried their head in the sand on this," she told BBC Sport.
"So World Rugby must really be commended for their bravery and integrity, for tackling this head on and following a science-based approach."
However, Loughborough University medical physicist and transgender woman Joanna Harper, who also attended the workshop, said she doesn't feel a ban would be right.
"I certainly understand all of that and I think putting restrictions on trans-women is a reasonable thing to do but I certainly don't agree with this idea of an outright ban," she told BBC Sport.
"I don't think this is necessarily the way to go. World Rugby has given us a month to issue responses and I will do so."
World Rugby's current transgender policy follows the International Olympic Committee's (IOC) policy.
Trans-gender weightlifter Laurel Hubbard has competed internationally for New Zealand. Photo: PHOTOSPORT
Guidelines issued by the IOC in November 2015 stated transgender women must suppress testosterone levels for at least 12 months before competition.
Testosterone is a hormone that increases muscle mass.
Athletes transitioning from female to male are allowed to participate without restrictions, but the IOC is currently developing new guidelines.
-BBC
