Athletics' governing body has denied blocking publication of a study which reportedly says a third of top athletes admitted violating anti-doping rules.
The Sunday Times said the International Association of Athletics Federations (IAAF) suppressed the survey, conducted at the 2011 Daegu World Championships.
But the IAAF said it had "never vetoed publication of this article."
Meanwhile, a German TV documentary claims four leading Russian athletes could face bans.
Responding to the Sunday Times story, the IAAF said that "this is not a new story", adding that the claims were initially made on German TV in 2013.
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The IAAF played no role in the study but said it was a "social science-based survey" conducted by the World Anti-Doping Agency (Wada) and a team of researchers at the athletes' village in Daegu, South Korea.
However the IAAF did have the power to veto its publication by Wada in return for allowing access to the competitors at Daegu.
The University of Tubingen in Germany, who conducted the study, said: "The IAAF's delaying publication for so long without good reason is a serious encroachment on the freedom of publication."
A leaked copy of the full study has been seen by The Sunday Times and the German broadcaster ARD/WDR.
On Sunday, the broadcaster said four Russian athletes and four officials face suspension if their national federation is unable to clear up suspicions of wrongdoing.
The newspaper reports that the survey concluded that 29%-34% of the 1,800 competitors at the championships had violated anti-doping rules in the previous 12 months.
It says that a month after collecting the information, the researchers were told to sign a confidentiality agreement to prevent them speaking out about the admissions.
The IAAF says it had "serious reservations" about the "interpretation of the results" made by the research group and submitted their concerns, but got no response.
UK Athletics chairman Ed Warner told BBC Radio 5 live's Sportsweek: "The IAAF believes that the scientific rigour of that survey didn't pass muster.
"They claim they've been conducting their own prevalence survey."
A Wada spokesman said: "Wada sought the agreement of the IAAF to carry out the project at the Daegu World Championships in 2011.
"Their consent was given so that researchers had access to athletes at the event, and was conditional upon any publication first being approved by the IAAF. The IAAF has not approved the publication of the project."