The lawyer of South Africa's Olympic champion Caster Semeny, barred from certain races unless she takes hormone suppressants, has told AFP he is preparing to approach the European Court of Human Rights to challenge the ban.
The 800m gold medalist Semenya has differences of sexual development (DSD), a condition that causes her body to produce elevated testosterone levels.
The World Athletics governing body in 2018 banned Semenya and other DSD athletes from races between 400 metres and a mile unless they take hormone-suppressing drugs.
The South African has previously challenged to the ruling but was unsuccessful in her plight.
"It didn't come as a complete surprise," Semenya's lawyer Gregory Nott said in an interview on Wednesday, noting that Swiss federal court cases were "very difficult to win".
"As usual in Caster's being, she took it very strongly and very well," he recalled. "She is also up for further fighting."
Nott said a legal team was preparing the paperwork to take the case before the European court (ECHR) -- a process that would take "a few more months".
Semenya would then decide whether to proceed or not, he added.
Nott has represented Semenya since she was forced to undergo gender verification testing to compete against women in the 2009 Berlin world championships.
She won gold in the 800m, aged 18, and was subsequently put on medication to reduce her testosterone levels -- spending six months sidelined by World Athletics before returning to competition.
Semenya was raised as a woman, identifies as a woman and races as a woman.
But World Athletics say female runners with some masculine attributes like Semenya have an unfair advantage in certain races.
"World Athletics has always maintained that its regulations are lawful and legitimate... and (are a) proportionate means of ensuring the rights of all female athletes to participate on fair and equal terms," the international federation said in a statement.
Despite the legal dispute, Semenya is setting her sights on the Tokyo Olympics, postponed to 2021 due to the coronavirus pandemic.