The Del Fuegos star makes the big reveal in an unauthorised biography about the leader of the Heartbreakers, and he insists Petty is OK with the news going public.

Haynes, who travelled the world with Petty and The Heartbreakers in the late 1980s, tells The Washington Post, "The first thing he (Petty) said to me on the subject is, 'I am very concerned that talking about this is putting a bad example out there for young people. If anyone is going to think heroin is an option because they know my story of using heroin, I can't do this'."

The rocker claims Petty opened up about his drug abuse hell in the 2007 documentary Runnin' Down a Dream, but then had a change of heart and insisted the scenes in which he discussed his heroin use were cut.

Petty never told Zanes why he turned to heroin but the biographer believes it had a lot to do with his divorce from first wife Jane Benyo and the fact that his bandmate Howie Epstein was also hooked on the drug. The bass player died of a heroin overdose in 2003.

Petty: The Biography is released next month (Nov15).