One doping case unearthed

The athlete concerned would not be identified until next week under the rules of the governing body of world athletics, the Senegalese said.

"I'm pleased to announce that with the support of the Japanese anti-doping agency we have been able to carry out the most comprehensive testing programme in the history of these championships," Diack said.

"I have been informed that we do have one adverse result but we will not be able to confirm the name or nationality of the athlete as we are still in the early stages of the process."

From the start of pre-competition testing on August 20 to the end of Saturday's competition, 1060 doping controls involving 926 athletes had been carried out.

Of those, 550 were urine tests and 510 blood samples have also been analysed, officials said.

"It is essential that we convince our young athletes that you can reach the top without doping," Diack added.

There were two doping violations at the last World Championships in Helsinki, nine in Paris in 2003 and a record high 13 in Edmonton two years earlier.