The stepfather of reigning six time MotoGP world champion Valentino Rossi is reported to have committed suicide.

According to the ANSA news agency, 52-year-old Mauro Tecchi - second husband of Rossi's mother Stefania Palma - killed himself with a shotgun wound to the chest at Pesaro in Italy. His body was found on Friday.

"I feel terrible, I do not know what to say," commented Rossi.

Rossi will start Sunday's Australian Grand Prix from second on the grid.