American former MotoGP champion Nicky Hayden has died of severe brain damage five days after he was hit by a car while cycling in eastern Italy, Italian media reported on Monday.

The 35 year-old, who rode for the Red Bull Honda team, was taken to Cesena's Maurizio Bufalini hospital last Wednesday after being struck by a car while training on his bicycle along Italy's Adriatic Coast.

A spokeswoman for the hospital could not immediately confirm the reports, which were carried by La Repubblica, Il Mattino and Fatto Quotidiano newspaper websites, among others. She said a statement was expected later in the evening.