World 400m champion Salwa Eid Naser has been provisionally suspended after failing to make herself available for anti-doping tests.
Nigeria-born Naser, who switched allegiance to Bahrain six years ago, ran 48.14 seconds - the third fastest 400m time ever - to take gold at the World Championships in Doha last October.
However, the 22-year-old has now been charged with a whereabouts failure by anti-doping authorities.
World Athletics rules stipulate that athletes will be guilty of a violation if they have a combination of three missed tests or filing failures across a 12-month period.
Athletes face up to a two-year ban for whereabouts violations.