World athletics' governing body (IAAF) has suppressed a 2011 survey that reveals up to one-third of the world's top competitors admitted using banned performance-enhancing techniques, Britain's Sunday Times and ARD/WDR German TV have reported. The study was carried out by researchers at the University of Tuebingen in Germany, who conducted confidential interviews with athletes at the 2011 world championships in Daegu, South Korea, the reports said. The International Association of Athletics Federations told the newspaper they were still in negotiations with the study authors and WADA about its publication. The results of the study showed that 29-34 percent of the 1,800 competitors at the championships had violated anti-doping rules in the previous 12 months. "These findings demonstrate that doping is remarkably widespread among elite athletes, and remains largely unchecked despite current biological testing programmes," the study said. A month after collecting the information and analysing it, they were told to sign a confidentiality agreement and have now criticised the IAAF for preventing its publication. "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 statement added the IAAF had not commissioned the survey, but had used its influence to suppress the findings, which have been leaked to the Sunday Times and ARD/WDR.