London: "Harry Potter" star Daniel Radcliffe's co-stars have warned him of serious health problems if he doesn't quit smoking 20 cigarettes a day.

Radcliffe has been nicknamed Harry Puffer on the set of the new Potter movie as he rushes off to smoke between takes. He is reportedly smoking a pack a day and this is worrying his friends, thesun.co.uk reports.

A source said: "Daniel has recently been smoking up to 20 cigarettes a day. 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."

Producers are also afraid that Radcliffe's image could be damaged if he is seen smoking in public.

"He's been having late nights out with stars like Kevin Spacey and Stephen Fry and seems to have picked up bad habits ...," the source added.