Calls mounted on Monday for more stringent punishments for dope cheats in athletics after two of the world's fastest men tested positive to banned drugs.
High-profile sprinters Tyson Gay and Asafa Powell failed controls for prescribed substances, sending shockwaves through athletics just over a month away from the Moscow world championships.
The International Association of Athletics Federations (IAAF) said the results indicated its drug-testing programs were effective.
"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."
Current and former athletes and administrators expressed concern at the wider impact of the news - and called for a tougher line on drug cheats.
The 1996 Olympic 100m champion Donovan Bailey of Canada described the revelations as "very sad for the sport" and "very disappointing".
"It's two of the veterans in track and field that I would never have expected this sort of news," he told Sky Sports News television. "I hope there will be some sort of explanation."
Britain's Denise Lewis, who won heptathlon gold at the 2000 Sydney Olympics, added: "It knocks the sport.
"It damages the confidence that people have, not only in the Jamaican team but the US team, because they've had a big drugs scandal some years ago."
Britain's 2004 4x100m relay gold medallist Darren Campbell called for a life ban for all drug cheats.
"Who does it need to be before you go 'okay, enough's enough'? It's ridiculous," he said.
A recent series of drugs scandals in athletics suggests the sport has yet to shake off the scourge of doping, with retrospective testing forcing the International Olympic Committee to re-award medals sometimes up to eight years later.
Before the 2011 world championships, where the IAAF introduced biological passports for athletes, Jamaica's Steve Mullings - previously sanctioned for testosterone use in 2004 - was banned for life after testing positive for a masking agent.
Four other Jamaicans including Yohan Blake - the main rival to double Olympic champion Usain Bolt - tested positive for the stimulant methylhexanamine before the 2009 edition and were banned for three months.
The 2003 championships were held after) revelations from the BALCO scandal, in which high-profile athletes, including US sprinter Marion Jones, were supplied with performance-enhancing drugs.
Gay, who was one of the figureheads of a USADA program against the use of performance-enhancing drugs, and Powell on Sunday confirmed separately that they had tested positive for a banned substance.
The US sprinter, the 2007 100m champion and the fastest man over the distance this year, and the Jamaican, a former world record holder in the straight sprint, both then withdrew from the world championships.
Gay, who is awaiting the results of his B sample after the stimulant oxilofrine was detected, said he had "never knowingly or wilfully" taken any banned substances.
Share
