Paris, France (AFP) — The 18-year-old 400-metre sensation Christine Mboma will be barred from the event at the Tokyo Olympics due to elevated testosterone levels, Namibia’s National Olympic Committee (NOC) said yesterday.

Mboma ran the seventh fastest women’s one-lap time in history when she clocked 48.54secs in the Polish city of Bydgoszcz on Wednesday.

The Namibian NOC said Mboma and her compatriot Beatrice Masilingi, also 18, had been tested at a training camp in Italy.

“The results from the testing centre indicated that both athletes have a natural high testosterone level,” the committee said in a statement.

“It is important to understand that both our athletes were not aware of this condition” and nor were their families or their coach.

World Athletics prohibits women who have high levels of testosterone, which gives them added strength, from competing in races between 400m and a mile unless they undergo treatment to reduce the levels.

Under the same rule, South African Olympic champion Caster Semenya will be barred from defending her 800m title in Tokyo.

Mboma and Masilingi will still be able to compete in the 200m at the Olympics, although their best times in the event do not currently put them in contention for a medal.