Olympics: The International Olympic Committee today said a case of "systematic planned doping" appears to have been uncovered following last week's suspension of seven top female Russian athletes.
The seven are accused of tampering with urine samples and the International Association of Athletics Federations has provisionally suspended the women, five of whom were due to compete in Beijing.
They include 800m and 1,500m runner Yelena Soboleva and 2004 silver medallist Tatyana Tomashova. Both could face four-year bans under new rules.
Soboleva has vowed to fight the provisional suspension.
Arne Ljungqvist, chairman of the IOC's medical commission and also vice-president of the world anti-doping agency Wada, said: "This does seem to be an example of systematic planned doping, and under the new Wada code that would mean an expanded ban of four years.
"The federation have done a very good job in revealing a very bad doping story which is just frustrating to find.
"It's sad and very disappointing that this type of planned cheating is still going on.
"There is a due procedure for the Russian federation to follow but the data is convincing and the DNA analysis is 100 per cent.
"If the urine is proved to not be theirs then they certainly have a case to answer."
Ljungqvist said between 4,500 and 5,000 drugs tests - more than ever before - would be carried out at the Beijing Games, some of them targeted at athletes who have raised suspicions they may be using banned drugs.