International Olympic Committee (IOC) president Thomas Bach says entire Russian sports federations could be suspended if allegations of state-supported doping at the Sochi Winter Games are proven.
Russia is at the heart of the biggest doping scandal in sport, with its track and field athletes suspended pending an investigation into allegations of widespread doping and their participation at August's Rio Olympic Games in doubt.
Bach said in an op-ed piece on Wednesday that accusations of Russian officials subverting the drug-testing system at the 2014 Games "represent a shocking new dimension in doping" and an "unimaginable level of criminality".
He said if the allegations were found to be true, sanctions could include Olympic life bans, tough financial penalties and "suspension or exclusion of entire national federations" like the one already imposed by the IAAF on Russia's track and field program.
Bach added that under such a scenario, athletes from affected nations may be required to prove their innocence rather than vice-versa.
"It (the IOC) would have to consider, whether in such 'contaminated' federations, the presumption of innocence for athletes could still be applied, whether the burden of proof could be reversed," he wrote.
Russia's sports ministry said on Wednesday it fully supported IOC actions to bar athletes who doped from competitions, but said clean athletes should not be excluded from the Rio Games.
"We strongly believe that clean athletes, who have spent years of their lives training for the Games, should not be deprived of the right to participate," the ministry said in its statement.
"Moreover, we are willing to fully cooperate with WADA (World Anti-Doping Agency) in their investigation and we have officially informed WADA of this."
Bach's statement came a day after the IOC announced 31 athletes from 12 countries could be barred from August's Summer Olympics in Rio, after doping samples from the 2008 Beijing Games came back positive in re-tests.
IOC vice-president John Coates moved to emphasise the probability of grave consequences for Russia if, as expected, its athletes represented a large proportion of those 31 implicated from the 454 re-tested samples.
"The more that it appears systemic, the more likely it is that there will be a collective decision that all of a particular national federation will go out," Coates said in Sydney on Wednesday night.
"I don't know where these athletes come from, I don't know what the sports are.
"It may be that if there's a significant number from another international federation ... we'll also put them out.
"If it is a significant problem in a particular sport then yes, absolutely.
"There'll be no political interference with this."
The IOC is also retrospectively testing some 250 samples from the London 2012 Games, and expects to have the results within the next week.
Coates, who's also the Australian Olympic Committee president, said he had confidence in the integrity of Rio's drug testing lab.
"It has been only recently re-accredited by WADA," Coates said.
"There is an observer program at Games that monitors how it operates.
"The very fact that it got accredited is encouraging for us, but I'm sure WADA is going to be all over it to make sure we don't get a repeat of Sochi."
