Three-time champion Alberto Contador on Thursday attributed his failed doping test to "food contamination" through meat during the previous Tour de France.
Other participants had also eaten the meat, but were not tested for doping, Contador said at a press conference in Pinto near Madrid, DPA reported.
The amount of the banned substance clenbuterol that appeared in the test was extremely low, Contador stressed.
"This is a real error," Contador said. "I think this will be resolved in a clear manner, with the truth brought forward."