Reigning Tour de France champion Alberto Contador is not guaranteed a starting place in the 2008 race.
Contador wants to win an Olympic gold medal at the Beijing Games
The Spaniard has signed for the disgraced Astana team, who were forced to withdraw from last year's event following a string of doping scandals.
Patrice Clerc, president of Tour organiser ASO, said: "When we make our selection, we don't pick individual riders but rather the teams.
"Let us have the time to calmly make our decision."
Contador joined Astana on a two-year deal at the end of 2007 when the Discovery Channel team disbanded.
Levi Leipheimer and Andreas Kloeden are also part of the Luxembourg-based outfit.
Astana had troublesome 2007. Not only did they miss the Tour de France, they were also excluded from the Tour of Spain.
Lead rider Alexandre Vinokourov was also fired after testing positive for a blood transfusion, while Andrej Kashechkin and Matthias Kessler have also failed doping tests.
I'd like to do well in the Olympic Games, but the rest of the focus will be the same as in the past
Astana claim to have cleaned up their act since then, but the team have been left shocked by the news that they have not been invited to compete in the 2008 Giro d'Italia.
Another high-profile outfit, High Road, which was formerly T-Mobile and boasts American George Hincapie as one of its riders, has also been left out of the 21-team race, which runs from 10 May to 1 June.
"We are stunned," said Astana spokesman Philippe Maertens. "We don't see the logic of this decision.
"I don't believe there is another team which practises as much internal anti-doping control as we do."
Contador has already said his main focus in 2008 is defending his Tour title, but also wants to win a gold medal at the Beijing Olympics.
"The Tour de France is my big goal and also the Olympic Games," said the Madrid-born 25-year-old.
"It's a big event, one that happens only every four years. I'd like to do well in the Olympic Games, but the rest of the focus will be the same as in the past."
Giro d'Italia teams:
ProTour (14): AG2R (FRA), Caisse d'Epargne (ESP), Cofidis (FRA), Euskaltel (ESP), Francaise des Jeux (FRA), Gerolsteiner (GER), Lampre (ITA), Liquigas (ITA), Quick Step (BEL), Rabobank (NED), Saunier Duval (ESP), Silence-Lotto (BEL), CSC (DEN), Milram (ITA).
Non ProTour (7): Barloworld (ENG), CSF Group (IRL), Diquigiovanni (VEN), LPR (IRL), NGC Medical (SUI), Slipstream (USA), Tinkoff (ITA).