Tour de France winner Alberto Contador has protested his innocence after testing positive for a banned substance during this year's race.
The Spaniard tested positive for clenbuterol on July 21 but claimed at a press conference near Madrid today that the cause was contaminated food.
Contador said: "It's a case of contaminated food of which I am the victim."
Astana rider Contador, who also won the Tour de France in 2007 and 2009, was earlier today provisionally suspended by the Union Cycliste Internationale (UCI).
The UCI said in a statement that only a small amount of clenbuterol had been found in Contador's urine sample.
Their statement said: "The UCI confirmed today that Spanish rider Alberto Contador returned an adverse analytical finding for clenbuterol following the analysis of urine sample taken during an in-competition test on July 21, 2010 on the second rest day of the Tour de France.
"This result was reported by the WADA accredited laboratory in Cologne to UCI and WADA simultaneously.
"The concentration found by the laboratory was estimated at 50 picograms which is 400 times less than what the anti-doping laboratories accredited by WADA must be able to detect."
A B sample confirmed the initial test result, leading the UCI to provisionally suspend Contador.
The UCI said: "This case required further scientific investigation before any conclusion could be drawn.
"The UCI continues working with the scientific support of WADA to analyse all the elements that are relevant to the case. This further investigation may take some more time."