Screaming fans of actor James McAvoy turned out to catch a glimpse of the star at the world premiere of his new film.

Filth, based on the Irvine Welsh novel of the same name, was launched at the Vue cinema at the Omni Centre in the author's home town of Edinburgh.

James McAvoy plays the lead role of corrupt policeman Bruce Robertson who is on track for a promotion and is determined to get it.

He causes conflict between his colleagues by exposing their secrets and stealing their wives while his drug habit spirals out of control.

Among those attending last night's premiere was, Irvine Welsh; Jon S Baird who is the film's writer and director, producer Ken Marshall and actress Shirley Henderson who previously starred in Trainspotting.

Before the screening, James McAvoy heaped praise on the book's author as well as the film's writer/director while fans screamed for his attention.

"Irvine's writing is incredible, he is unique on this planet and he is a really special and important voice but his books don't always translate perfectly to the screen if you keep their structure . That's understandable because they are different mediums.

"You have to fashion a narrative and a structure from his excellent writing, and that's what Jon (S Baird) has done."

Commenting on the unsavoury nature of his character, McAvoy said: "I don't really care what people think of me. It's just a case of, are people going to want to sit through and watch this guy do such terrible things, and I think hopefully they will.

"Not everybody will because some of it is just too graphic and too dark but hopefully the people who stay after the first five minutes will enjoy it."

Irvine Welsh has co-produced the film and is delighted with the final product. He said: "It is a very very strong film and I think it is going to be a big cultural moment in British cinema.

"It is a stand-alone movie, I think it really rocks."

Talking about his inspiration and focus on dark subjects, he said: "I like it when people are having a bad day, in terms of drama, that interests me. When people are having a bad day, they can do silly and crazy things.

"They make the sort of decisions that compounds their misery, you learn more through failure than you do through success.

"So I'm fascinated by failure basically and by the way that we self-sabotage and make the wrong decisions when we are under pressure.

"Everything is from past experience and everyone has bad days but hopefully not to that extent (of the lead character).

"I'm quite a happy camper, my bad days and moods don't last for long. But you're looking at the world and the people around you and trying to empathise with what they are going through and that's where the material comes from I think."

Filth will be released in Scotland on Friday and the rest of the UK and Ireland a week later on October 4.