Explainer-What is World Athletics' proposal to tighten transgender rules?

The World Athletics Council is voting on Thursday on a proposal to change its rules on transgender women athletes that would make it harder for them to compete in women's track and field events.

Here is an explanation of what the proposal is and the governing body's reasoning behind the change:

WHY IS WORLD ATHLETICS VOTING ON TRANSGENDER ELIGIBILITY RULES?

Transgender rights have become a major talking point as sports seek to balance inclusivity with ensuring there is no unfair advantage. LGBTQI advocacy groups say excluding trans athletes amounts to discrimination.

World Aquatics voted last year to restrict participation of transgender athletes in elite women's competitions and create a working group to establish an "open" category.

At the time, World Athletics president Sebastian Coe praised swimming's governing body for taking the decision and said the World Athletics council would also discuss its regulations.

WHAT IS WORLD ATHLETICS' PROPOSAL?

In January, World Athletics said it was consulting with member federations on a proposal to change the rules on participation of transgender women in female competitions.

The governing body said it arrived at its "preferred option" after reviewing a number of new and existing scientific studies and observations from the field.

WA said "We will follow the science... in order to protect the female category, maintain fairness in our competitions, and remain as inclusive as possible."

That option is to halve the current maximum amount of plasma testosterone permitted for transgender women and those with differences in sex development (DSD) to 2.5 nanomoles per litre from the current 5 nanomoles.

The proposal also doubles the time an athlete needs to remain below the new 2.5 nanomoles