LAUSANNE, Switzerland, Sept 8 (Reuters) - Double Olympic 800 metres champion Caster Semenya has lost her appeal to the Swiss Federal Tribunal (SFT) to set aside a 2019 Court of Arbitration (CAS) ruling that female athletes with high natural testosterone levels must take medication to reduce it.

But the South African has indicated that she may continue her battle in the European and domestic courts ahead of the Olympics in Tokyo next year, vowing to "fight for human rights".

Semenya approached the tribunal in May last year after CAS, sport's highest court, ruled that the regulations of the sport's governing body World Athletics were necessary for athletes with differences in sexual development (DSDs) in races ranging from 400 metres to a mile to ensure fair competition.

The tribunal found that subjecting female athletes to drug or surgical interventions as a precondition to compete does not amount to a violation of Swiss public policy.

Testosterone increases muscle mass, strength and haemoglobin, which affects endurance. Some competitors have said women with higher levels of the hormone have an unfair advantage.

"I am very disappointed by this ruling, but refuse to let World Athletics drug me or stop me from being who I am," Semenya said in the statement on Tuesday. Read more via Openly