Disgraced sprinter Ben Johnson claims he was framed over taking drugs and that doping is still rife across professional sport.
Johnson was stripped of his Olympic 100m gold in 1988
Johnson told BBC Five Live: "People are evil. They will do anything to get rid of someone from the sport.
"I don't want to get myself in trouble, but I would say 40% of people in sports are using performance-enhancing drugs.
"You would be surprised to see the great players of the past who retired doing stuff."
Johnson tested positive for steroids at the 1988 Olympics and was stripped of his 100m gold and world record.
But he claims that he was the victim of a sting designed to incriminate him.
He said: "People can put things in your food and drinks to sabotage you, like they did to me in Seoul in 1988."
Simon Clegg, chief executive of the British Olympic Association, hit out at Johnson's comments.
Clegg told BBC Five Live: "I do not accept the figures that Johnson has said. I think that is totally ridiculous.
"We have a very good record, particularly in this country, of running a high-quality anti-doping programme that ensures that cheats are caught and that athletes are aware of the medical downsides of taking banned substances."
Johnson told Sportsweek: "I'm not a cheat - I do what I am supposed to do to win.
"I'm not saying go ahead and take it (drugs), but it's not a crime. It's just in some sports it's banned, some it isn't.
"Most of my people here in Canada and in the world still look at me as the fastest man in the world. They say I'm the fastest ever, dead or alive."
Banned for life
Johnson tried to make a comeback after being banned for four years following his positive test, but trailed home last in his first-round heat at the 1992 Games.
He then tested positive again in March 1993 and was banned from athletics for life, leaving him an itinerant who briefly coached Diego Maradona and was once hired by Colonel Gaddafi to train his son Al-Saadi.
Johnson predicted better things for Britain's Dwain Chambers, who returns from his own drugs ban later this month.
"I don't think people in Europe will point the finger at him. People will say, hey, you're back again, I'm happy to see you on the circuit again.
"People will find good things to say about him, not bad things.
"I would say to him just to be careful who he has around him, and to be careful who he eats with."