As many as 99% of Russian athletes are guilty of doping, a German TV documentary has alleged.
The programme claims that Russian officials systematically accepted payment from athletes to supply banned substances and cover up tests.
The documentary, shown by Das Erste, also implicates the International Association of Athletics Federations (IAAF) in covering up the abuse.
The Russian Athletics Federation (RAF) says the allegations are "lies".
However, both the IAAF and the World Anti-Doping Agency (Wada) have said they will look into the claims.
The IAAF said it had "noted a number of grave allegations" and revealed that an investigation into some of the claims was "already ongoing".
The BBC has not independently verified the documentary's allegations and is awaiting responses from athletes targeted in the programme.
In the documentary, broadcast on Wednesday, former discus thrower Yevgeniya Pecherina claimed that "most, the majority, 99%" of athletes selected to represent Russia use banned substances.
"You can get absolutely everything," added the 25-year-old Russian. "Everything the athlete wants."
Pecherina is currently serving a 10-year doping ban that is due to end in 2023. She had already been handed a two-year suspension in 2011.
Liliya Shobukhova, who won the London Marathon in 2010, is also interviewed in the programme and admits paying the Russian Athletics Federation 450,000 euros (£350,000) to cover up a positive doping test.
She is currently serving a two-year ban after irregularities were detected in her biological passport.
The documentary also included an undercover video purporting to show 800m runner Mariya Savinova, who won gold at the 2012 Olympics in London, admitting to using the banned steroid oxandrolone.
The video was dubbed into German with the original audio track absent, but the channel said it possessed an unedited version.
Athletes tweet reaction to doping claims: |
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Women's marathon world record-holder and former world marathon champion Paula Radcliffe: "Sick to my stomach. Some of the allegations coming out of this are every sport's worst nightmare."
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Four-time Olympic rowing gold medallist Sir Matthew Pinsent: "This is grim reading for Olympic sports fans - it casts a pall over every Russia performance for an Olympiad."
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German pole vaulter and reigning world champion Raphael Holzdeppe: "Yesterday's documentary was shocking. We can only continue to set a good example and keep pursuing clean sport."
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The claims of widespread wrongdoing stem principally from former Russian Anti-Doping Agency (Rusada) official Vitaly Stepanov and his wife Yulia (nee Rusanova), formerly an 800m runner who was banned for doping.
They allege that leading Russian athletics officials supplied banned substances in exchange for 5% of an athlete's earnings and colluded with doping control officers to hush up and falsify tests.
Yulia Stepanova said it was also common for Russian athletes to avoid out-of-competition testing by using false names while training abroad.
Wada said that the claims would be "carefully scrutinised", adding that it had "already received some information and evidence of the type exposed in the documentary".
It added it had passed the information on to be investigated by "the appropriate independent body" within the IAAF.
A Wada statement concluded: "If action is warranted, Wada will take any necessary and appropriate steps under the code."
According to some reports, the RAF will hold an emergency meeting later on Thursday, but RAF president Valentin Balakhnichev told news agency Reuters that the documentary's allegations were "a pack of lies".
Rusada managing director Nikita Kamaev added: "We believe that the speculation and the statements are completely unfounded."
But International Olympic Committee spokesman Mark Adams told the Associated Press: "These are serious allegations. Should there be anything affecting the IOC and our code of ethics, we will not hesitate to take any and all action necessary."
Russia, which hosted the Winter Olympics in Sochi earlier this year and finished top of the medal table, currently has 67 athletes serving sanctions for doping offences, according to the latest IAAF report.
In September, Wada banned the gas xenon following allegations, in another German TV documentary, it had been used as a performance-enhancing substance by Russian competitors at Sochi.
Rusada has said it has a rigorous testing system and conducts around 20,000 tests per year.
Last year, there were calls to boycott the World Athletics Championships in Russia because of links to doping.
