Athletes Sara Moreira of Portugal and Lim Hee-nam of South Korea have been suspended after failing doping tests at the world championships in South Korea.
The IAAF says both tested positive for the banned stimulant methylhexaneamine and have been provisionally suspended for two years, pending the outcome of their respective disciplinary hearings.
Moreira, 26, a 5,000 metres bronze medalist at last year's European Championships in Barcelona, who has won three gold medals with the Portugal team at the European cross country championships, finished 12th in the 3,000 metres steeplechase final in Daegu.
Lim was in the South Korean 4 x 100 metres relay team that finished fifth in its heat.
They were among 468 athletes tested for urine during the championships that were held in Daegu in late August to early September.