Ian Thorpe's return to racing has been further delayed with the five-time Olympic gold medallist pulling out of the Santa Clara grand prix meet.

Thorpe was due to compete at the Californian meet on Saturday but a Swimming Australia spokesman confirmed Thorpe's withdrawal.

Thorpe has not raced since the Commonwealth Games trials in February in Melbourne.

Australia's most decorated Olympian missed the Melbourne Games due to a bout of glandular fever and then sustained a broken hand.

He is due to fly out of Australia for a three-month training stint at top college USC, after only briefly returning home having recently completed promotional activities in Japan this week.