World 400m champion Salwa Eid Nasar has been provisionally suspended after breaching anti-doping rules relating to the whereabouts system.

The 22 year-old Bahraini became the first ever Asian woman to win the event when she ran 48.14 to dominate the final in Doha last October.

It was the third fastest time in the history of women’s 400m running as she eased to gold, beating Olympic champion Shaunae Miller-Uibo in the process.

But she now faces the prospect of a two-year ban from the sport after failing to inform anti-doping officials of her whereabouts.

A violation of the system can range from as serious an offence as three missed tests or simply filing failures over a 12-month period.

Naser was the favourite to win the 400m in Rio this year before the Olympics were pushed back to 2021.

And despite the postponement of the Games, she could still miss them if found guilty of the doping offence.