Lia Thomas, the transgender swimmer who was barred from competing in women's events, has lost her case against World Aquatics at the Court of Arbitration for Sport (CAS).

The decision prevents the American from having any chance of competing at the Paris Olympics, which begins on July 26.

Thomas became the first transgender NCAA champion in Division I US collegiate history in 2022.

But World Aquatics (then known as FINA) voted to restrict the participation of transgender athletes in elite women's competitions.

Thomas had lodged a case with CAS in January in a bid to overturn the ban and compete in elite female races again, arguing that the provisions were "invalid and unlawful", and also discriminatory.

"World Aquatics welcomes the recent decision made by the Court of Arbitration for Sport (CAS) regarding the case of Lia Thomas, which we believe is a major step forward in our efforts to protect women's sport," World Aquatics said in a statement.

"World Aquatics is dedicated to fostering an environment that promotes fairness, respect, and equal opportunities for athletes of all genders and we reaffirm this pledge.

"Our policies and practices are continuously evaluated to ensure they align with these core values, which led to the introduction of our open category.

"We remain committed to working collaboratively with all stakeholders to uphold the principles of inclusivity in aquatic sports and remain confident that our gender inclusion policy represents a fair approach."

Thomas had expressed a desire to compete for a place at the Olympics before the new rule was adopted by World Aquatics.

Reuters