Alberto Contador's lawyers challenged a reported World Anti-Doping Agency document Wednesday that concludes his positive Tour de France test could not have been caused by tainted meat.

El Pais newspaper said a WADA team visited the slaughterhouse and butcher's shop in Irun, Spain, that provided the beef Contador contends led to the positive finding for clenbuterol.

El Pais said it obtained a WADA report that determined the clenbuterol in Contador's sample "could not have come from possibly contaminated meat" and also ruled out asthma medication as a cause.

"None of the inspections and none of the tests on samples of meat found traces of clenbuterol, a banned drug used to fatten cattle quickly," El Pais said.

In a statement released by Contador spokesman Jacinto Vidarte, the rider's legal team said that after studying all the material it received from the International Cycling Union - including the WADA report - "it is impossible to determine that the meat was not contaminated."

Contador's legal team argued that WADA's investigation "lacked strength" since it did not investigate all the possibilities of food contamination and was limited to questions - rather than actual analysis - related to the slaughterhouse and ranch where the meat came from.

"The European Union's present system of monitoring meat is not perfect nor sufficient enough in detecting fraud where it exists," the Contador statement said.

Contacted by The Associated Press, WADA spokesman Frederic Donze declined comment.

Contador, a three-time Tour de France champion, remains provisionally suspended. He risks losing his latest Tour title and a two-year doping ban if found guilty of doping.

The WADA report was passed on to the Spanish cycling federation from the UCI. The Spanish disciplinary committee is investigating Contador's case and will issue a ruling.

The 27-year-old cyclist, who has threatened to quit the sport regardless of the outcome, said he would be willing to submit all of his team's own investigation to the Spanish federation and meet with the panel in the coming days.

According to El Pais, WADA's report said Contador's "main problem" to prove his innocence is that "his entire defense rests on the involuntary ingestion of the meat contaminated with clenbuterol in such a tiny amount that it had no effect on his performance."

WADA referred to a 2008 European Union study in which 300,000 meat samples were tested and traces of clenbuterol were found in only one. It added that farmers will not slaughter their cattle until at least 20 days after the last dose of clenbuterol has been administered to avoid being caught and allow the steroid to have its full "fattening-up" effect.

Contador signed a two-year deal to ride for Team Saxo Bank-SunGard from 2011.