Richie Porte's start in the Giro d'Italia may be in question, with the Australian admitting that the illness which has recently led to his withdrawal from two World Tour events has "compromised" his preparation for the three-week race.

Speaking from his European home in Monaco on Friday, Porte said his program hinged on talks with his Sky team principal David Brailsford and his trainer Tim Kerrison.

Australian cyclist Richie Porte's immediate future is under a cloud. Credit:Getty Images

Porte, who has been preparing to lead the British Sky team for an all-out assault on the Giro from May 9 to June 1, has been stricken with gastroenteritis that last week forced him out of the March 12-18 Tirreno-Adriatico race in Italy with three stages remaining.

After returning to Monaco to recover, he started the seven-day Volta a Catalunya in Spain on Monday, but withdrew on Tuesday during stage two.