OLYMPIC drug testing has been dismissed as a fiasco by a top doping expert. The attack by one of the world's leading researchers in the field of drugs in sport came as the International Olympic Committee was meeting in Rome yesterday to discuss whether to re test the positive samples of at least four athletes from the Atlanta Games.

Chuck Yesalis, a Penn State University epidemiologist, criticised drug testing procedures in Atlanta after the IOC admitted that the unnamed athletes had been detected taking drugs by the high resolution mass spectrometer (HRMS), but that they had decided not to accept the results because the equipment was previously untested.

IOC medical director Prince Alexandre de Merode said after yesterday's meeting that there were in fact five cases, but the IOC had decided that the samples would be used for research purposes and would not therefore be retested. "The five cases are now closed," he said.

Yesalis said that "the pre Olympic publicity campaign about the HRMS's increased sensitivity that could potentially produce many more positive tests in Atlanta was nothing more than a public relations campaign attempting to scare athletes into not taking drugs."

He has been critical of the IOC's lack of proper scientific standards and views the current controversy over the HRMS results as another example of insufficient research.

When he criticised them for not spending enough on scientific validation of their drug testing methodologies at a conference in Sweden last November, several members of IOC accredited labs privately thanked him, he said.

Dr Don Catlin, who was in charge of steroid testing in Atlanta and revealed the outstanding positive test results, believes that the use of the HRMS was a step forward for the IOC. He said that the machine is an advance because it can detect low levels of substances that the normal mass spectrometers might miss.

It is the machine's sensitivity, however, that appears to have caused the confusion over the status of the urine tests in question. These tests revealed low levels of substances that normally appear in a person who has consumed a banned substance. The IOC medical commission, however, is not convinced that these traces of steroids constitute doping.

Sixteen athletes returned suspicious urine samples at this year's Atlanta Olympics although only two Bulgarian women's triple jumper Iva Prandzheva and Russian women's high hurdler Natalya Shekodanova - were banned for doping, IOC medical director de Merode said yesterday.

De Merode told a news conference that another two cases were "discussed and abandoned", seven cases involving bromantan were rejected on "juridical grounds" and another five steroid cases were rejected because of technical doubts. Bromantan will be banned by the IOC from February 1997.

He said that because of technical advances made since the Games, he was confident that all 16 samples would now fail dope tests if carried out under similar circumstances in a few months time.