The proposed two-year ban stems from a blood sample collected during last year's Tour de France that was later linked to the wide-ranging Operation Mountain Pass blood-doping investigation in Spain.
The blood sample was taken during an Italian stage of the event, Italy's ANSA news agency said Wednesday.
Valverde, a world-class road racer, has repeatedly denied doping. However doping prosecutors with the Italian Olympic Committee say the blood sample he gave during the Prato Nevoso stage revealed DNA that matched plasma stored by the doctor who was the lead target in Operation Mountain Pass.
Blood doping for cyclists involves transfusions of blood that have had plasma removed, which gives it a higher concentration of red blood cells that enable the rider to better resist fatigue during endurance races like the Tour de France.