Remy Di Gregorio of FranceLAURENT CIPRIANI/The Associated Press
Prosecutors called for French Tour de France rider Remy Di Gregorio to be charged with "possession of banned substances or illegal devices" on Thursday.
Di Gregorio was arrested with two others on Monday night while on the Tour and was transferred to his home town of Marseille, where he was heard by investigating magistrate Annaick Le Goff.
"The rider denies any doping practices," Marseille prosecutor Jacques Dallest told reporters.
He said one of those arrested, a Marseille naturopath, had admitted to injecting ozone into Di Gregorio's bloodstream.
"He said he injected ozone into the rider's bloodstream twice. During another meeting, he had taken a blood sample that he enriched with ozone before injecting it again," he said, adding that the two had met four times between the end of May and end of June this year.
"During another meeting, he injected a dose of 250 ml of glucose into the rider. Those two practices are forbidden," said Dallest.
Dallest said other products found in phials were being analysed by the French gendarmerie after they were seized from a third person travelling from Marseille to Bourg en Bresse where Di Gregorio was staying.
Di Gregorio was provisionally suspended by his Cofidis team on Tuesday.