EDMONTON, Canada World indoor 3,000 meters champion Olga Yegorova, who was embroiled in a drug scandal last week, is one of at least seven distance runners whose urine has been chosen for tests for the banned drug epo (erythropoietin).

International Association of Athletics Federations (IAAF) Medical Chief Arne Ljungqvist said on Tuesday that seven to 10 of the 39 athletes who provided blood and urine samples before the world championships would stay in the epo analysis process.

Ljungqvist made it clear that none of the athletes, including Yegorova, had failed the tests for the stamina-boosting drug, Reuters said.

Drug testers first analyse the blood of the athletes. If they find the blood values are outside certain parameters, another test is ordered to focus on epo.

Yegorova's parameters were borderline but Ljungqvist said she had been selected for further tests after the controversy of a recent test in France.

"About a third of the athletes will have their urine analyzed," Ljungqvist said. "Yegorova is one of them. But you can get different parameters for many reasons. You can get them because you are temporarily dehydrated."

Yegorova tested positive for epo at the Paris Golden League meeting last month and was suspended from the championships last Thursday pending the result of a second analysis of her urine.

But the Russian, who has denied taking the drug, was cleared by the IAAF because the International Olympic Committee (IOC) requirement for a joint blood and urine test had not been followed. Only a urine test had been carried out.