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 21st July 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."
Contador, speaking in his home town of Pinto near the Spanish capital, told journalists his version of events leading up to his positive test.
He said: "I was informed of this on August 24th by the UCI and on the 26th I met with them to give my version.
"The organiser of the Vuelta a Castilla y Leon came to the Tour and our cook asked if he could bring some good meat.
"This person bought this meat in a shop on the way to France. I don't know where the shop gets their meat supply from.
"He arrived that day and on the afternoon of the 20th, a day before our rest day, the meat was cooked."
Contador said he was not the only rider to eat the meat, but that he was one of the only ones who had who was tested afterwards.
"I was told that the only rider to go through a test after the meat was Aleksandr Vinokurov, but because he went down to dinner early, he didn't eat any and because we don't usually eat meat on rest days, so as not to put on weight, he didn4t ask for it either," Contador said.
"He went to the control with me, but he hadn't eaten the meat.
"Of all the other riders, none went through the control.
"I told all of this to UCI.
"The UCI understands perfectly what has happened. This is a different case because it's a clear case of contamination, incomparable to any other Clenbuterol case.
"It's such a minimal amount that it it's only possible to come from a food contamination. And in terms of performance it would not be any use at all - any expert can confirm this."
When asked about his mood, the 27-year-old said: "I'm sad and disappointed but I can hold my head high because with the truth in front of me I can talk loud and clear.
"I've spent a month and half keeping this inside, without sleeping. My family didn't find out until last night."