Spain's Juan Jose Cobo has been found guilty of an anti-doping rule violation based on "abnormalities" in his biological passport between 2009 and 2011, the International Cycling Union (UCI) said on Thursday.
Cycling's world governing body has imposed a three-year suspension on the now retired 38-year-old, with Spanish media reporting that he could also be stripped of his 2011 Vuelta a Espana title.
That would mean Briton Chris Froome, who finished second ahead of Bradley Wiggins in the race, could be awarded the victory for his seventh Grand Tour crown.
"The anti-doping tribunal found (Cobo) guilty of an anti-doping rule violation based on abnormalities from 2009 and 2011 detected in his biological passport and imposed a three-year period of ineligibility on the rider," UCI said in a statement.
"In accordance with the procedural rules of the anti-doping tribunal, the decision will be published on the UCI website in due course."
A biological passport is an electronic record where results of all doping tests by a rider over a period of time are collated and compared.
The UCI said that Cobo had used a prohibited substance but did not state what it was.
Cobo can appeal the decision before the Court of Arbitration for Sport within a month.
Meanwhile, Froome will remain in intensive care in France for the next few days following a crash at the Criterium du Dauphine that ruled him out of the Tour de France, Team Ineos said on Thursday.
The four-times Tour champion sustained multiple fractures including broken femur, elbow and rib bones when he crashed at high speed while checking the course ahead of the individual time trial on Wednesday.
Froome underwent surgery for six hours on broken bones on Thursday.
"Chris woke up this morning and was reviewed by intensive care consultants and the orthopaedic specialist who operated on him and they're both very happy with his progress," team doctor Richard Usher said in a statement.
"He will remain in hospital for the next few days for observation, but he's already actively engaging in discussing his rehabilitation options, which is very encouraging.
"As he begins his road to recovery, the team will now only be providing further updates at a stage where it is necessary."