The world athletics governing body (IAAF) has been accused of withholding the results of a 2011 survey, in which up to a third of competitors admitted to using banned performance-enhancing techniques.

The survey revealed 29 to 34 per cent of the 1,800 competitors at the 2011 world championships in South Korea violated anti-doping rules in the previous 12 months.

Britain’s Sunday Times and Germany’s network ARD/WDR alleged the authors of the study were told to sign a confidentiality agreement a month after the damaging information was collected.

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The revelations were the latest in a series of damaging blows for the sport in the countdown to the start of this year’s world championships in Beijing on August 22.

The survey was conducted at the 2011 Athletics World Championship in South Korea. Photo: Getty

Earlier investigations by ARD and the Sunday Times prompted claims more than 800 athletes tested between 2001 and 2012 had suspicious test results that were not followed up by the IAAF.

The IAAF has since taken disciplinary action against 28 athletes from the 2005 and 2007 world championships.

The organisation came under heavy fire from the authors of the 2011 study, which was conducted by researchers at the University of Tuebingen in Germany.

“The IAAF’s delaying publication for so long without good reason is a serious encroachment on the freedom of publication,” the researchers said in a statement.

The IAAF had not commissioned the survey but had used its influence to suppress the findings, the researchers said.

“These findings demonstrate that doping is remarkably widespread among elite athletes and remains largely unchecked despite current biological testing programmes,” the study itself concluded.

The study was financed by the World Anti-Doping Agency, which said it gave the IAAF the power to veto its publication.