Swimming's world governing body FINA voted to restrict the participation of transgender athletes in elite women's competitions and create a working group to establish an "open" category for them in some events as part of its new policy announced on Sunday.
Transgender rights have become a major talking point as sports seek inclusivity while ensuring there is no unfair advantage.
The debate intensified after University of Pennsylvania swimmer Lia Thomas became the first transgender NCAA champion in Division I history after winning the women's 500-meter freestyle earlier this year.