According to documents sent to the World Anti-Doping Agency (WADA) by doping expert Werner Franke, 2007 Tour de France winner Alberto Contador was involved in a Spanish drugs scandal.

The results from the Spanish investigation of a blood-doping scandal were sent to both WADA as well as Germany's federal police last week. Franke, a molecular biologist, said the details of specific banned substances Contador received from Spanish doctor Eufemiano Fuentes were contained in a file called "Document 31."

Alberto Contador earned his first career Tour de France victory on July 29 in Paris.
(Franck Fife/Getty Images)

Fuentes was at the centre of Operation Puerto, one of cycling's biggest-ever doping cases, which was launched in May 2006 when a Madrid clinic was raided after allegedly providing doping services to more than 50 riders.

Montreal-based WADA president Dick Pound told the Suddeutsche Zeitung newspaper his organization would defer to national authorities and cycling's world governing body, the Union Cycliste Internationale (UCI).

Pound also said that if WADA becomes dissatisfied with the action taken by those groups, it could get involved in the case and take it to the world sport's highest court, the Court of Arbitration for Sport (CAS).

German rider Joerg Jaksche, who was Contador's teammate at Liberty Seguros and the first rider to admit doping through Fuentes, has added to the controversy by expressing a willingness to testify for WADA.

His initials "J.J." were on Fuentes's customer list right next to the officially unidentified "A.C.," which is suspected of referring to Contador. Jaksche has admitted that the "J.J." initials were his.

"I can only tell you I am J.J. in Document 31 and that I doped, like it says there," said Jaksche, who maintains that he never witnessed Contador taking any banned substances.

Contador has never failed a doping test and maintains that he was mistakenly named in the Puerto file.

"I was in the wrong team at the wrong time and somehow my name got among the documents," Contador said, adding that the UCI had corrected the mistake.

Contador, who now rides for the Discovery Channel team, missed the 2006 Tour when the Liberty team, including four other riders, the team director and doctor, were all allegedly linked to Operation Puerto.

With files from the Associated Press