Two cyclists at the Giro d'Italia were on Tuesday knocked off their bikes by metal barriers that were blown across the seafront home straight by a powerful blast of air created by a low flying television helicopter.

Italy's Luca Wackermann was knocked unconscious and was rushed away by ambulance, while Etienne van Empel escaped with a few cuts after the pair were taken out on the final stretch of the fourth stage in Sicily on Tuesday.

Race organizers RCS say the television helicopter used by state broadcaster RAI was the vehicle involved.

Sports director of the Vini Zabu team Francesco Frassi said later both his riders were okay.

"Luca came round in the ambulance, he couldn't remember a thing though," Frassi said.

Race organizers say they the pair will be credited as finishing the stage and can continue with stage five on Wednesday.