Sir Steve Redgrave has dismissed claims by disgraced sprinter Dwain Chambers that only athletes who use drugs can win Olympic titles.
Chambers told BBC's Inside Sport programme that scientists would always be one step ahead of the testers.
But Redgrave, the winner of a record five Olympic rowing gold medals, angrily rejected Chambers' view.
"What he had to say is ridiculous. I competed for 25 years and never took an illegal drug in my life," he said.
Chambers, the former European 100m champion, served a two-year ban for taking the designer steroid THG in 2003.
He decided to switch to American football for financial reasons and is currently training with the Hamburg Sea Devils in NFL Europe.
Redgrave added: "Sprinters can be insular and a law unto themselves. If they aren't getting the best results they think everyone else is cheating to get there.
"I never considered taking drugs. For me it was about trying to become the best athlete I possibly could and by doing that I managed to win some Olympic medals."
European cross-country champion Mo Farah also branded Chambers a loser.
"I train so hard and for him to say you can't do it without cheating is wrong," he said.
"I believe that if you train your hardest you can achieve. Look at Paula Radcliffe. She trains hard and that is why she does incredible things.
"How does she set a world record and he doesn't? I had these dreams as a kid and I still have them - I want to go as far as I can and do the best I can."