Olympics chief Thomas Bach called for a complete overhaul of the anti-doping system on Tuesday after revelations of state-backed cheating by Russia rocked preparations for the Rio Games.

The uncovering of Russia's widespread doping had shown up deficiencies in the system run by the World Anti-Doping Agency, Bach told an IOC session in Rio.

"Recent developments have shown that we need a full review of the WADA anti-doping system," Bach said, in a bullish speech just three days before the Olympics open on Friday.

"The IOC is calling for a more robust and efficient anti-doping system," he added. "This requires clear responsibilities, more transparency, more independence and better worldwide harmonisation."

A report by Canadian lawyer Richard McLaren for WADA said Russia's sports ministry and secret services evaded drug testers by switching samples at Russian laboratories.

The IOC has come under fire after it stopped short of banning Russia completely from Rio, but instead left it to individual sports to take action against athletes from the country.

Bach blasted an outright ban as a "nuclear option", adding: "Let us just for a moment consider the consequences of a 'nuclear option'. 

"The result is death and devastation. This is not what the Olympic movement stands for."

Source: AFP