VANCOUVER and WHISTLER - Anti-doping officials are promising the toughest drug testing yet during the Vancouver Olympics, and they say more than 30 athletes have already been caught in the months leading up to the Games.

The International Olympic Committee plans to conduct 2,500 tests during the Games, about 70 per cent more than in the 2006 Olympics in Turin, Italy. The tests include 500 blood tests to check for human growth hormone, as well as new tests to target EPO, or erythropoietin, a banned drug that stimulates red blood cell production, useful for endurance events.

The World Anti-Doping Agency, or WADA, said Thursday that more than 30 athletes had tested positive in the months leading up to the Games, and that none of them will be in Vancouver.

John Fahey, WADA president of the international agency that co-ordinates drug testing in sports, refused to provide a specific figure or reveal any names, nationalities or sports involved.

Mr. Fahey insisted that it was up to national sports federations to reveal the names of the athletes.

By contrast, more than 70 athletes tested positive before the 2008 Summer Olympics in Beijing, although more than twice as many athletes participated in those Games. Similar figures were not available for the Turin Games, officials said.

"I think [the 30 tests] indicates that we are effective," Mr. Fahey said. "More importantly, it means that there are 30 less cheats in Vancouver."

David Howman, WADA's director-general, said many of the names have already been made public in various countries.

He would not provide details.

"You don't have to be a rocket scientist to see that there were quite a number in cross-country skiing, and a few in biathlon and so on," he said.

Officials with the Canadian Olympic Committee said they had not been told that any Canadians were among those who tested positive.

The IOC formally began testing at Vancouver on Feb. 4, and no positive tests have been announced. Prior to that date, testing was done by sports agencies in each country. Officials are hoping the tough policy will be an example for professional sports leagues, including the National Hockey League.

"There will always be athletes, and certainly their entourage, who will attempt to get an edge over their competitors in any possible way," Mr. Fahey said. "It's more likely that they will be caught [during the Vancouver Olympics] than in any other Games in our history."

Mr. Howman said WADA's testing policy has applied to NHL players selected for the Games since last October, although he did not know if any hockey players were among the 30 athletes who tested positive.

He added that WADA has been working with NHL commissioner Gary Bettman and the NHL Players' Association on a testing policy for the league that would be in line with WADA's code.

Former WADA president Dick Pound, who has sharply criticized the NHL, said Thursday that "NHL testing still lags behind other [sports leagues], except for the [Canadian Football League], which has none."

Mr. Fahey said drug testing is getting better in part because agencies are working with police in several countries.

He also rejected concerns by some athletes that tougher anti-doping rules are infringing on their civil liberties. For example, many athletes have criticized so-called "whereabouts rules" that require them to be available for testing at almost any time. Failing to show up, without a valid excuse, can lead to sanctions.

Most of the recent drug cases involving Winter Olympic athletes have been for blood doping - the boosting of oxygen-carrying red blood cells by transfusion methods or drug use.