Paris - Athletics' world governing body on Monday said that the anti-doping system was working, after top sprinters Tyson Gay and Asafa Powell returned positive tests, sending shockwaves through the sport.
The International Association of Athletics Federations (IAAF) said it had an "unwavering" commitment to root out drug cheats, as it had a duty to the majority of athletes who believed in clean competition.
"It is for them that we have built a programme that is well-resourced, far-reaching and sophisticated," the IAAF said in an emailed statement.
"The fact that we are able to detect and remove from the sport athletes who have breached our anti-doping rules should be seen in this context.
"The credibility of our anti-doping programme, and the sport of athletics, is enhanced, not diminished, each time we are able to uncover a new case and we have the committed support of every athlete, coach or official who believes in clean sport."
Gay and Powell - two of the four fastest men in history - on Sunday both confirmed separately that they had tested positive for a banned substance.
US sprinter Gay, the 2007 100m world champion and the fastest man in the world this year, and Powell, a former world record holder in the straight sprint, will now not compete in next month's athletics world championships in Moscow.
Gay, who is awaiting the results of his B sample after a banned stimulant was detected, said he "never knowingly or wilfully" taken any banned substances.
Powell, meanwhile, was reportedly one of five athletes who failed drug tests at Jamaica's national trials last month in Kingston.