World 1500m champion Abeba Aregawi has been provisionally suspended after testing positive for a banned substance.
The 25-year-old Ethiopia-born Swede failed an out-of-competition test conducted by governing body the IAAF.
Aregawi, who won gold at the 2013 World Championships in Moscow and 2014 World Indoor Championships in Sopot, has requested a B sample be tested.
Britain’s Hannah England finished fourth behind Aregawi in Moscow.
There is no suggestion Aregawi’s performance in that race is under scrutiny.