"By 2000, unless we are testing blood, we haven't got a chance," Cowan told an anti-doping conference in Dublin, organised by the Olympic Committee of Ireland.
Cowan, who supervised the establishment of the $8m (pounds 5m) drug testing centre in Kuala Lumpur used at the recent Commonwealth Games, has also been involved in recent research to discover an acceptable test for substances such as human growth hormone (hGH) and erythropoietin (EPO).
He said a $3m research project, funded by the IOC and the European Union, has discovered reliable blood tests for EPO and hGH.
Cowan said he hoped the tests will be accepted when the IOC stages an international symposium on drugs in Switzerland next February. EPO and hGH are believed to be in widespread use throughout international sport.
Spot checks by police and customs officials in Australia and France during the past year uncovered large quantities of the drugs in the possession of coaches and competitors at the swimming world championships and the Tour de France cycle race.
At the end of last week at the Dublin conference, Dr Jim McDaid, Ireland's sports minister, announced plans to introduce legislation to gaol athletes caught using performance-enhancing drugs.
"If I can find the means within Irish law, I will not hesitate to apply criminal sanctions, including gaol terms, to those who contaminate sport with drugs," McDaid announced.
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