Controversial transgender swimmer Lia Thomas is taking secret legal action in a bid to overturn a ban on biological males competing alongside women – and hopes to take part in the Paris Olympic trials, according to a report.

Thomas, 24, has hired the Canadian law firm Tyr to ask the Court of Arbitration for Sport in Switzerland to overturn the rules imposed by World Aquatics after she became the first openly trans person to win an NCAA Division I title, the Telegraph reported.

She has not competed since 2022, when World Aquatics introduced rules that prohibit anyone who has undergone “any part of male puberty” from the female category.

Prior to that, trans women were allowed to compete if they lowered their testosterone levels.

Tyr describes its staff as “fearless advocates” who have been involved in “high-stakes and precedent-setting cases” – but those brought before the CAS are controversially heard behind closed doors unless those involved agree to publicize them, according to the outlet.

​When Thomas took up the case at the tribunal in September, World Aquatics applied to have it thrown out because she had not submitted herself to the jurisdiction of USA Swimming, the Telegraph reported.

A month before Thomas’ March 2022 NCAA win, USA Swimming imposed stricter transgender regulations, which stopped short of an outright ban but required regular monitoring of such athletes’ testosterone levels.

“It’s been a goal of mine to swim at Olympic trials for a very long time, and I would love to see that through,” she told “Good Morning America” less than a month before World Aquatics introduced its own policy in June 2022.

Thomas’ case is unlikely to be heard in time for her to qualify for this summer’s Olympics, according to the outlet.

The deadline for entry to the trials is June 4, but she would have to win the case several weeks earlier to allow her the opportunity to submit times in May that would be good enough for her to enter the trials that begin June 15, the Times of London reported.

World Aquatics declined to comment on Thomas’s legal challenge.

Its executive director, Brent Nowicki, said in a statement to the Telegraph: “The World Aquatics policy on gender inclusion, adopted by World Aquatics in June of 2022, was rigorously developed on the basis of advice from leading medical and legal experts, and in careful consultation with athletes.

“World Aquatics remains confident that its gender inclusion policy represents a fair approach and remains absolutely determined to protect women’s sport,” he added.

It is unknown when Thomas transitioned from male to female, but the swimmer competed as a man as recently as November 2019

She has always denied transitioning to be successful.

“The biggest misconception, I think, is the reason I transitioned,” she said in 2022. “People will say, ‘Oh, she just transitioned so she would have an advantage, so she could win.’ I transitioned to be happy, to be true to myself.”