Anti-drugs chief Dick Pound believes a number of cross-country skiers have been doping at the Turin Olympics.
Twelve athletes were suspended for five days to reduce abnormal levels of haemoglobin - which boosts the blood's oxygen supply - prior to competing.
The International Ski Federation (FIS) said the ban was to protect the skiers' health and was not a drug issue.
"Frankly, we think we are dealing with doping," said World Anti-Doping Agency (Wada) boss Pound.
"It's too much of a coincidence to have 12 athletes with hugely high Hb [haemoglobin] levels just before the Games."
Athletes who were found to have acceptable levels of haemoglobin after five days were cleared for competition, including Olympic champion Evi Sachenbacher.
But on Tuesday, Belarus' Sergei Dolidovich was handed a second five-day ban.
Haemoglobin is a naturally occurring protein inside the body's red blood cells which allows oxygen to be transported.
The more red cells there are in your body, the more oxygen that can be delivered to the muscles, delaying the onset of fatigue.
But an athlete's red blood cell count can also be boosted by banned drugs such as EPO.
The FIS says that the initial test results were caused by high-altitude training, but Pound suggests the organisation is sweeping the issue under the carpet.
"I think we are going to have another look (after the Games)," said Pound.
"It is easier to deal with it as a health problem than as a doping problem.
"The FIS might be afraid that they are not able to prove that they were drugged."
The 12 skiers failed tests before the start of the games, eight on Thursday and four on Friday.
Of those 12, seven have subsequently been cleared to compete, one failed a re-test and the other four have yet to be cleared.