The 65-year-old Belgian had predicted on the eve of the Games that he expected there to be between 30-40 positive tests, extrapolated from previous Games and the fact there would be many more tests.

Thus far there have been five such cases – though Greece's 2004 Olympic 400 metres hurdler Fani Halkia was tested at a pre-Games training camp - with the latest being a positive A sample for Ukraine's heptathlon silver medallist Lyudmila Blonska.

Rogge, though, said that he could see discernible progress being made against one of the main sicknesses affecting sport in general.

"I am a very modest man, but we are making progress in the fight against doping in sport," he said.

"There were 12 positive tests in Sydney and 26 in Athens and one could say at the same time that if we do not reach that number (his estimate of positive tests here) then the deterrent factor is working. If there are more tests then athletes get scared about resorting to doping."

Rogge said that one of the improvements that had been made since Athens was that the federations had taken on board advice from the IOC about dope testing.

"Prior to the Athens Games there were 26 positive tests discovered by international federations, especially in weightlifting. We said to the federations that they should begin their pre-Games testing earlier for these Olympics.”

"Thus in the six weeks leading-up to the Games there were 39 athletes who tested positive in particular the Greeks and the Russians. It means that there have been 39 cheats thwarted from coming to the Games and affecting the results."

Rogge reiterated that even those athletes who perhaps had got hold of so-called designer drugs - which are at present undetectable - could not be sure of getting away with it in the long term as there was no statute of limitations on drugs cheats.

"That is the reason why we freeze the samples," said Rogge.

"They can be opened up at any time once we have the knowledge of how to detect a drug and then test for it. It is far more difficult to cheat now.”