MONACO -- Three positive doping tests involving athletes not yet identified are being investigated in samples taken from the track and field world championships held in London this month.
"None of the adverse findings relate to medalists," the IAAF's independent integrity unit said.
The unit said details of the cases will be revealed "at relevant points of the disciplinary process."
The three cases emerged from 1,513 blood and urine samples collected and analyzed during the competition period. It means less than 0.2 percent of doping control samples were positive.
The IAAF's anti-doping unit said samples will be stored for 10 years to be re-analyzed when new testing methods are developed.
The integrity unit also said no suspect betting activity was detected during the 10-day championships.