Moscow: Russia must step up the fight against doping or risk staining its 2014 Sochi Winter Games, International Olympic Committee vice president Thomas Bach told reporters.
Bach`s warning came just days after IOC chief Jacques Rogge urged Russia to step up its anti-doping efforts following a "worrying" series of high-profile bans.
Russia has been in the doping spotlight in recent years with many of its top summer and winter athletes testing positive for banned substances.
Top cross-country skier Alena Sidko, considered a medal contender at the Vancouver Olympics, became the most recent big-name offender just weeks before the start of the Games.
Three other leading Russian skiers, triple Olympic champion Julija Tchepalova, 2006 Olympic gold medallist Yevgeny Dementiev and national champion Nina Rysina, have also been banned.
"My impression is the Russians have understood and they realise that if they would have a problem with doping, if Russia would be perceived as not fighting against doping as much as other countries, that this would cast a shadow on the Sochi 2014 Games," Bach said.
"The (IOC) disciplinary commission issued another warning before the Games to the team of Russia," Bach, a German lawyer, said.
So far the Feb. 12-28 Vancouver Games have only had one positive case, with Russian ice hockey player Svetlana Terenteva receiving a reprimand for testing positive to a light stimulant.
"I have been at Games where in the first week I have not been watching a single sports event (because of dealing with doping cases)," Bach said.
"I am happy to report that here until now at least I could attend one event per day and this as a sports fan that makes me happy," said Bach, a 1976 Olympic fencing gold medallist.
Bach, who also heads the IOC`s commission in charge of legal matters and is a potential frontrunner to succeed Rogge in 2013, said testing procedures have become smarter.
"The measures do not begin with the Games. They start a year before, when the IOC in close cooperation with different international federations and the World Anti-doping Agency is already knitting the net tighter," he said.
"(In Vancouver) there are 70 percent more tests than in Turin (in 2006.) We test the first five finishers, plus two (randomly) plus an intelligent target testing," he said.
The IOC also freezes the samples for eight years until tests are developed for substances that the IOC may not have been aware of at the time of the Games.
"Every potential cheat now knows that in six months, in one year, in two years he can be sanctioned even if he thinks that now the prohibited substance he takes cannot be detected."
The IOC has also set up an entourage commission, which among other things will look at doping that may be linked to the athletes` coaches, agents or doctors.
"Athletes themselves, they are very well addressed by the sports authorities, the WADA code, by the sanctions in place."
"But we are not so much effective in the athletes` entourage when it comes to doctors prescribing prohibited substances, when it comes to dealers or others," he said.