The 18-year-old actor has reportedly been dubbed "Harry Puffer" due to his 20-a-day cigarette habit. Radcliffe's co-star Rupert Grint has allegedly been urging him to give up.
An insider revealed: "Every time they call 'Cut', he lights up. It's disgusting.
"Friends and co-stars including Rupert Grint have been warning him about the dangers of smoking. But he doesn't take any notice.
"He's been having late nights out with stars like Kevin Spacey and Stephen Fry and seems to have picked up bad habits from the luvvie set."
It was recently announced that Harry Potter and the Deathly Hallows, the final book in the wizard series, will be made into two films by studio Warner Bros.
> Should Radcliffe be banned from smoking? Share your views