BEIJING--The Beijing Olympic Games seem to have become a clean Games despite the final number of doping cases has yet to be announced.

The Beijing lab will not finish analyzing all the samples until Wednesday, so the International Olympic Committee president Jacques Rogge would not give his final judgement but he was confident that the Games had seen improvement in the fight against doping.

President of the International Olympic Committee (IOC) Jacques Rogge smiles during a news conference in Beijing August 24, 2008. [Agencies]

"We have six positive cases now. If you look at the mathematical extrapolation from the number of positive cases of Sydney and Athens, it will end up between 30 and 40 possible cases here," said Rogge.

"I am glad to say that most of the athletes, the overwhelming majority is clean but the small amount who cheat unfortunately tainted the whole sport," he said.

Ukrainian weightlifter Igor Razoronov, 38, became the latest athlete tested positive when the IOC on Saturday announced the sixth finisher in men's 105kg was tested positive for the steroid nandrolone.

On the previous day, Razoronov's compatriot Lyudmila Blonska was ordered to give up her silver medal in women's heptathlon at the Games for using steroid Methyltestosterone.

DPK Korean shooter Kim Jong-su was the first medalist found using banned substance at these Games. He had to surrender his silver in the 50m pistol and bronze in the 10 air rifle.

Athens champion Fani Halkia of Greece was stripped of her accreditation before she could defend her 400m hurdles. The IOC found traces of steroid Methyltrienolone and asked the Greek authorities to investigate Chalkia's coach George Panagiotopoulos for possible anti-doping rule violation.

Spanish cyclist Isabel Moreno and Vietnamese gymnast Thi Ngan Thuong Do are another two offenders.

There were 12 doping cases from around 2,500 tests in Sydney in 2000 and 26 positive cases were found in Athens where 3,600 tests were carried out.

Rogge said he was confident that tough measures against doping already proved effective although the number of doping cases has not been finalized.

"We believe we have had less cases because the deterrent factor worked," he said. "It has become more difficult to cheat because we have increased the number of tests  from 3,600 in Athens to more than 5,000 now."