BEIJING - Improved technologies for catching athletes who use the banned substance human growth hormone (HGH) are reliable and will not lead to false positive tests, a top Olympic official said on Thursday.

An earlier test for HGH was introduced by the World Anti-Doping Agency (WADA) in 2004, but production was halted two years later when the company producing the necessary antibodies was taken over by another firm, which decided to halt manufacture.

"The Games will never be a field of experimentation," Patrick Schamasch, the International Olympic Committee's (IOC) medical director, told reporters.

"It's so important for the athlete to be treated fairly, even if they cheated," he said on a tour of the anti-doping laboratory for the Beijing Games.

"We are using the tests which are duly validated and reproduceable in different laboratories and which have been totally validated by WADA," he said.

The Beijing Olympics, which open on August 8, will see over 4,500 athletes tested for banned substances -- more than at any other Games -- in an effort to curb cheating and recover the reputation of elite-level sport after several high-profile scandals.

Officials will also be able to test athletes more than once in the same day, and even the possession of a prohibited substance will constitute a violation of the rules.

HGH is a naturally occurring hormone, but administered artificially, it stimulates muscle and tissue growth.

WADA officials have said the window of detection between the ingestion of the hormone and a possible positive test had been expanded beyond the original 48-hour limit, but Schamasch would not be drawn on the timeframe, saying he did not want to tip off cheats.

He said it was highly unlikely that drugs such as steroids or hormones in meat could cause false positive tests.

"It is very, very unlikely to have such a contamination happen.... You can be sure there will be no false positives because of that," Schamasch said.

The 2004 Athens Olympics opened with a drugs scandal and witnessed 26 positive tests for banned substances.

International Olympics Committee president Jacques Rogge was quoted as saying that as many as 40 competitors could test positive during the Beijing Games.