Rebellin, who also won an individual stage in the 1996 Giro d'Italia, was killed instantly in the incident, which occurred at Montebello Vicentino shortly before midday, local newspaper Il Gazzettino reported.
The report added that the vehicle did not stop at the scene and that police were looking for it and the driver.
Rebellin, who was ordered to return his road race silver medal from the 2008 Olympics in Beijing after a retroactive doping test, retired earlier this year after three decades in professional cycling.