A survey that revealed up to a third of top athletes admitted using banned performance-enhancing techniques was allegedly suppressed by the sport’s governing body. The results of the study showed that 29 to 34 per cent of 1,800 competitors broke anti-doping rules, the Sunday Times and ARD-WDR German TV have claimed.

It was carried out by researchers at the University of Tuebingen in Germany, who carried out confidential interviews with athletes at the 2011 world championships in Daegu, South Korea.

The International Association of Athletics Federations (IAAF) told the newspaper it was still in negotiations with the study authors and the World Anti Doping Agency (WADA) about its publication.

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

Researchers allege 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.

They added the IAAF had not commissioned the survey but had used its influence to suppress the findings.

The lead author, Rolf Ulrich, said his team had been barred from discussing their work. He said: “The IAAF is blocking it. I think they are stakeholders with WADA and they just blocked the whole thing.”

The study was financed by WADA who told the newspaper it had given the IAAF the power to veto publication in return for allowing access to the athletes at Daegu.

Some of the study was leaked in America in 2013 but the governing body prevented the full publication of the findings, the newspaper alleged.

The IAAF has denied suggestions any veto took place. “The IAAF has never vetoed publication of this article,” it said in a statement.

“The IAAF does however have serious reservations as to the interpretation of the results made by the research group as confirmed by high-profile experts in social science who reviewed the publication on our request.

“The IAAF submitted those concerns to the research group but has never heard back from them.”