Former Tour de France runner-up Andreas Kloeden underwent an illegal blood transfusion during the 2006 race according to the results of an independent commission.
The two-year probe by the University of Freiburg, also reported doping with the banned blood booster EPO was systematic within Kloeden’s T-Mobile team from 1995.
The university’s three-man panel concluded that two doctors, Lothar Heinrich and Andreas Schmid, implemented a blood-doping programme within Team Telekom and its successor T-Mobile without the knowledge of the university.
They had 58,800 blood samples re-tested and interviewed 77 witnesses, including German rider Patrik Sinkewitz who served a one-year ban for doping, according to news agency Reuters.
"The final report concludes that apart from the rider Patrik Sinkewitz, who has confessed (to blood doping), there were at least two more riders who committed blood doping: Matthias Kessler and Andreas Kloeden," a statement read on the University of Freiburg's website.
The commission ruled in its final 63-page report, available on their website, that Kloeden, Sinkewitz and Kessler received transfusions from their own blood after the first stage of the 2006 Tour.
Kloeden, 33, now rides for the Astana team who would not immediately comment on the matter.
UCI president Pat McQuaid told Reuters: "We know the report has come out, it is in German so we will have to take the time to study it and to consult with the German Federation and the German Anti-Doping Agency before we do anything."
The report added that doping was a common practice within Team Telekom and its successor T-Mobile.
"Systematic EPO-doping within Team Telekom under medical instructions began at a training camp in Mallorca (Spain) in January 1995," the report said.
Meanwhile Belgian rider Tom Boonan faces a suspension of up to six months and is certain to miss the Tour de France after failing an out-of-competition test for cocaine, cycling officials have said.
It is the Belgian's second offence in 12 months after he also tested positive for the same substance in an out-of-competition control last year.
When the Quick Step rider's latest positive test was announced on Saturday the UCI said Boonen would not be punished by the governing body "since the use of cocaine out of competition is not subject to sanctions".
However, the UCI said on Tuesday: "The behaviour of Tom Boonen, even though it does not constitute a violation of the anti-doping rules, can be considered unacceptable and liable to harm the image, reputation or interests of cycling or the UCI.
"This infringement is punishable by a suspension of one to six months," cycling's governing body added, according to Reuters.
Tour de France organisers reacted to the UCI announcement by saying Boonen would take no part in this year’s race.
Quick Step had already suspended the rider for "an unspecified period of time" and said he would have to follow psychological or psychiatric treatment.
According to a Eurosport report on Saturday the rider blamed the incident on an alcohol problem. He said: “For 364 days it goes perfectly, but the one day that I drink too much I change.
“A day before the check I went out and ended up on a terrace. I hung around there a little too long. Then I had a blackout. When I go out, I clearly cross a line.”