The Canadian, who was later banned for life after testing positive for a second time, maintains he was a victim of sabotage at the Seoul Olympics.

But he believes nearly half of all sportsmen – from sprinters to baseball players and footballers – are deliberately cheating.

“I am saying 40% of people in sports are still using performance (enhancing drugs),” said Johnson.

“I think that based on past experiences I have had. It is not only track and field, there are soccer players, football players, basketball players, cyclists and you would be surprised that some of the great players are doing stuff.”

The claims were immediately rubbished by British Olympic Association chief executive Simon Clegg, who questioned the motivation behind Johnson’s statement.

“I am very disappointed to hear Ben say that and I don’t accept the figures,” he said. “It is totally ridiculous to think a significant number of people involved in high-performance sport are involved in performance-enhancing drugs.

“In this country we have a very good record of running a high quality anti-doping programme.

“I don’t think I know of any athlete who has been found guilty of a doping offence who has said ’I am one of very few number of people’.

“The normal excuse is ’I am one of many people and I am just unfortunate to have been caught’.”

Johnson seems to have conflicting views on the issue of performance-enhancing drugs.

On the one hand he insists it is “not a crime” and that people in Canada still regard him as the fastest man ever because “we do things to be the best we can be in our sport“.

But Johnson also maintains he was set-up at the Seoul Olympics and he had a word of warning for Dwain Chambers, the British sprinter who is looking to return to athletics after serving a two-year doping ban.

“I say to him be very careful what he does and who he surrounds himself with,” warned Johnson.

“Don’t eat (food provided by other) people too much because people can put things in your food and drinks as sabotage. That is what happened to me in Seol 1988.

“People will do anything to get ahead or get rid of somebody from the sport. Life is not supposed to be fair.

“I am not a cheat. I do what I am supposed to do to win. Most of the people here in Canada still look at me as the fastest man alive.

“I don’t think people will point the finger at him. People will recognise him as Dwain Chambers, he has run 9.97seconds before, he was banned for two years but he is back now and it is good to see him back on the circuit. People will find good things to say about him.”

Chambers will be welcomed back into athletics but unless he successfully challenges the BOA’s legislation, he will never run for Great Britain at the Olympic Games.

“Dwain has served his ban and is seeking to come back into the sport. It will be interesting to see what levels of performance he is going to achieve,” Clegg told BBC Radio Five Live’s Sportsweek programme.

“The BOA has an anti-doping bylaw that prohibits any athlete found guilty of a doping offence from representing our country at a future Olympic Games and Dwain falls inside that ban.

“Unless he appeals successfully he will not be part of the team in Beijing or London.

“This was brought onto the statute book as a direct result of pressure from the athletes and there is absolutely no stomach at the BOA for change.

“We believe it is absolutely right and proper that we set a high moral ground and tell the athletes who are found guilty of a doping offence ’you can come back into the sport but you will not represent your country at the Olympic Games’.