Daniel Radcliffe's friends have begged him to stop smoking. The Harry Potter star, who has become so addicted to nicotine that his co-stars have nicknamed him "Harry Puffer," has reportedly been asked by his co-stars to quit his 20-a-day cigarette habit.

Radcliffe, 18, has allegedly been puffing the cancer sticks every time they have a break at the set of the "Harry Potter and the Half-Blood Prince" movie.

An insider says, "Daniel has been smoking up to 20 cigarettes a day. Every time they call 'cut,' he lights up. It's disgusting.

"Friends, including co-stars Rupert Grint and Emma Watson, have been warning him about the dangers of smoking. But he doesn't take any notice."

The young actor reportedly finished a whole pack of cigarettes when he had to shoot a complex stunt last week.

The source adds to The Sun newspaper, "He was really nervous about the scene and was sparking up constantly."

The film execs are apparently worried about the film's star's habit. They are concerned this could damage his clean image and told him not to smoke in public.