USA Paralympic swimmer Becca Meyers has withdrawn from the Tokyo Paralympics because she was prevented from bringing her own assistant to the Games.
Meyers, who is deaf and blind, usually has her mother accompany her as a personal care assistant (PCA).
However, Covid safety restrictions mean there will be a single PCA for all USA Paralympic swimmers in Tokyo.
Myers, 26, says she is "heartbroken" at having to make the "gut-wrenching" decision to withdraw.
"I'm angry, I'm disappointed, but most of all, I'm sad not to be representing my country," she wrote on Twitter.
Meyers says the United States Olympic and Paralympic Committee (USOPC) has "repeatedly denied my reasonable and essential accommodation" that would enable her to compete in Tokyo.
Meyers' mother Maria has been her PCA at all international events since 2017. PCAs accompany Paralympic athletes throughout the Games, helping with a variety of tasks including navigating the different Paralympic venues.
"With Covid, there are new safety measures and limits of non-essential staff in place, rightfully so, but a trusted PCA is essential for me to compete," added Meyers.
"So, in 2021, why as a disabled person am I still fighting for my rights? I'm speaking up for future generations of Paralympic athletes in the hope that they never have to experience the pain I've been through. Enough is enough."
Meyers was set for her third appearance at a Paralympics having made her debut as a 17-year-old at London 2012, winning two silvers and a bronze, and then won three gold medals in Rio four years later.
The USOPC has been approached for comment.
Tokyo is currently battling a rise in Covid-19 cases as the city prepares for the Olympic Games opening ceremony on Friday, with a state of emergency declared throughout the city's hosting of the event.
Stringent health and safety measures are in place for athletes and officials, with no spectators allowed at any events in the Japanese capital.
The Paralympics are scheduled to begin on 24 August, with a decision on whether fans can attend to be taken after the Olympics.
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