TOUR DE FRANCE champion Alberto Contador’s contaminated beef defense will again be put to the test after the International Cycling Union decided today it would appeal the Tour de France champion’s acquittal from doping.

The UCI said it is going to the Court of Arbitration for Sport to challenge the Spanish cycling federation’s decision not to ban the 28-year-old Contador for his positive clenbuterol test.

“The International Cycling Union today decided — within the time frame stipulated by the regulations — to appeal to the Court of Arbitration for Sport in Lausanne against the Spanish Cycling Federation’s finding in the case of Alberto Contador,” the UCI said in a statement on the final day of the deadline for an appeal.

“The decision to appeal comes after an in-depth study of the file received from the (Spanish federation).”

Contador was acquitted after testing positive for clenbuterol during an in-competition test on July 21, 2010, a rest day during last year’s Tour de France. He blamed the finding on eating contaminated beef.

Contador spokesman Jacinto Vidarte said he would not immediately comment on the appeal. The World Anti-Doping Agency has three more weeks to decide if it will join the appeal.

WADA regards clenbuterol, a banned anabolic agent which burns fat and builds muscle, as a zero-tolerance drug. However, its rules allow athletes to escape a sanction if they prove “no fault or negligence” on their part.

If CAS finds him guilty of doping, Contador faces a two-year ban and losing his Tour victory. Contador can continue racing until CAS gives a verdict. He currently leads the weeklong Volta of Catalunya.

CAS has said it would try to deliver a verdict before this year’s Tour starts on July 2, allowing Contador a chance to defend his title if cleared.

The UCI announced last September that Contador was provisionally suspended after minute traces of clenbuterol were found in his system, and asked the Spanish federation to investigate.

The Spanish body’s disciplinary committee originally proposed a one-year ban for Contador in January. Contador’s legal team then offered new evidence and he was cleared to race three weeks later. Spanish Cycling Federation spokesman Luis Roman told The Associated Press:

“Now we are the judged, not the judges, along with Contador.”

Days before the decision to clear Contador, Spanish Prime Minister Jose Luis Rodriguez Zapatero had said “there’s no legal reason to justify sanctioning Contador.”

Contador resumed his career with new team Saxo Bank-Sungard and has since completed two races. He was fourth in the Tour of Algarve in Portugal and won the Vuelta of Murcia in Spain.

Team owner Bjarne Riis called for a quick ruling and said he was standing by his star rider.

“Alberto Contador was acquitted in the first place and therefore is innocent of any deliberate wrongdoing until a ruling says something else,” said Riis, the 1996 Tour winner who later admitted doping during his career. “As long as this is a case of accidental intake of a forbidden substance, we will continue to support Alberto Contador. In our opinion it would be unfair to do anything else.”

Contador is one of only five cyclists to win the three Grand Tours — the Tour de France, Giro d’Italia and Spanish Vuelta. He also won the Tour in 2007 and 2009, and was prevented from defending his first title in 2008 because his Astana team was banned for doping offences at the previous year’s race.

Only one cyclist has lost a Tour title for doping. Floyd Landis of the United States was stripped of his 2006 victory for testing positive for testosterone.