The announcement was made by race director Carmine Castellano while riders were meeting to decide whether to continue the rest of the tour.
After initial doubts, and a daylong meeting, riders decided to continue the rest of the tour Friday.
"Obviously they were not happy with what happened,'' Mauro Vegni, a race organizer, told The Associated Press in a phone interview from the Italian Riviera where the race was supposed to start on Thursday.
Initially, the difficult stage through the Alps was going to be shortened by 62 miles, but Vegni said the plan was dropped when it was realized the participants wouldn't have enough time to finish the course during the day because the riders' meeting was still going on.
On Wednesday evening, about 400 police officers raided hotels hosting all 20 teams in the race. The blitz, which lasted until 4 a.m. Thursday, was part of a crackdown on banned performance-enhancing substances.
The Carabinieri paramilitary police which conducted the raids said they seized some 200 packages of medicine, including stimulants, anabolic steroids and corticosteroids, as well as used syringes, the Italian news agency ANSA reported.
ANSA reported that the massage therapist for Mercatone Uno was led away by officers, and a cyclist, which it didn't identify, had jumped out of a first-floor window of his hotel during the raids. He was not injured and was stopped by police.
A police officer was hit by a syringe, without its needle, thrown from a hotel window, ANSA said.
Wednesday night's investigation was launched after syringes and other paraphernalia were found in hotels following the May 27 stage that finished in Reggio Emilia.
The reports of the raids are reminiscent of the 1998 doping scandal that hit the Tour de France when teams were expelled after admitting to widespread drug abuse and police raided hotels searching for banned substances.
Italian police performed similar raids in two previous Giro races, in 1996 and 1997. The first raid in the southeastern city of Brindisi turned up no significant evidence of doping violations after a news leak alerted suspects. In June 1997, Carabinieri searched the hotel rooms of the Technogym team in the northeastern city of Trentino.
Last week, police seized medicines in the caravan of top racer Ivan Gotti, who said the substances were to treat his allergies. ANSA reported that Gotti's father-in-law is being investigated for allegedly supplying banned substances.
Gotti, a two-time Giro champion in 1997 and 1999, was cleared of wrongdoing along with his wife. The Alessio team star is currently in eighth place.
Mercatone's top star, Marco Pantani, who won the Tour in 1998, pulled out of the Giro on Wednesday, saying he was too ill to continue. Pantani, who also won the 1998 Giro before facing a litany of doping accusations, was doing poorly in this year's event.
Before Wednesday's leg in San Remo, a French and an Italian cyclist were pulled out of the race by their respective teams after each reportedly tested "non-negative'' in a preliminary doping test.
Riccardo Forconi was pulled before the start of the stage by the same Mercatone Uno team that features Pantani.
Forconi was in 39th place before the start of the stage in this northwestern coastal city.
Earlier, the Alexia Alluminio team yanked French cyclist Pascal Herve. Test results on Tuesday indicated Herve had used the banned performance-enhancer EPO.
Thursday's stage, the 18th in the three-week Giro, was supposed to be one of the most difficult, taking riders on a 142.6 mile course through the Alps.