American motorcycling champion Nicky Hayden has died from injuries he sustained in an accident on his road bike last week, the Maurizio Bufalini hospital in eastern Italian city of Cesena tweeted on Monday.

Hayden had been in intensive care with severe head and chest injuries after he was hit by a car while driving along a road near the Adriatic coastal resort of Rimini last Wednesday.

Police had put the Bufalini hospital into lockdown to protect the privacy of critically-ill racer after swarms of US paparazzi reportedly tried to gain access to his bed, where he was on life support in an induced coma.

Well-wishers and fans also continued to arrived at the hospital, prompting Cesena police place to put cordon in place.

Good-quality footage from security cameras that a local resident handed to police show that Hayden ignored a Stop sign at a junction and was knocked off his bike by a passing car, it has emerged.

Investigators are also probing whether Hayden may have been distracted by listening to music, as headphones connected to an iPod were found at the scene of the accident.

Hayden, from Owensboro, Kentucky, was World Superbike Championship rider and won the MotoGP World Championship in 2006.