Lure of gold leaves Olympics prone to doping

And 1992 winner Linford Christie was refused a place on Britain's 2012 Olympic torch relay after he tested positive for the steroid nandrolone late in his career, although there is no evidence the Briton was on drugs when he triumphed in Barcelona.

Perhaps no former Olympic champion has fallen as far as Marion Jones, a triple gold medal winner at the 2000 Sydney Games, who is currently serving a six-month jail sentence in Texas for lying to investigators about her drug-taking.

US sports officials hope a line has been drawn under a dark chapter with the conviction in May of athletics coach Trevor Graham - who guided both Gatlin and Jones - for lying to federal investigators over the BALCO laboratory scandal which embroiled so many stars.

A doping furore nearly ruined the start of the Athens Olympics four years ago, when home sprint stars Kostas Kenteris and Katerina Thanou were allegedly involved in a motorcycle accident, apparently to avoid taking pre-competition tests.

Once the action got underway, Russia's Irina Korzhanenko was forced to hand back the women's shot putt gold medal after she was found to be taking the steroid stanozolol - the same substance Ben Johnson used 16 years earlier.