Clarke told the Australian Associated Press (AAP) on Wednesday that athletes should be permitted to use performance-enhancing drugs, including steroids and EPO, as long as they did not harm their health.

"If it's not dangerous, no (it should not be banned), it just levels the playing field," Clarke was quoted as saying.

"As soon as something comes along like EPO...they'll say it's a drug and you can't use it (but) it's the only thing that levels the playing field."

Clarke, a former multiple world record holder who retired in 1970, said athletes born at sea level should be allowed to use drugs to give them a fairer chance against competitors raised at altitude.

"There are two competitions in the world, the altitude runners and the others," he said.

"I'm not advocating drugs, I'm saying until there is a drug, there won't be any parity in any future competition.

"We'll never break another world record by our sea level athletes from 1,500m or above for another century."

Clarke broke numerous world records during his glittering career but never won the Olympic gold medal.