Chloe Moretz says her portrayal of Hit Girl in new movie 'Kick-Ass' is make believe and people shouldn't take it so seriously.

The 13-year-old British actress - who plays assassin Hit Girl in the comic book movie 'Kick-Ass' by director Matthew Vaughn - admits she is quite young to play a character who uses such obscene language and violence, but claims that's the whole point of acting because she understands she could never get away with it in real life.

She said: "It's a movie. Obviously a little girl can't beat up and kill huge, heavy men. I don't see how anyone would realise it's not real. It is a controversial role, but it was a role I wanted to do. If I said a sixteenth of the words I did in that movie at home, I would be grounded for the rest of my life for sure."

Some critics claim Chloe - who was just eleven when she played the superhero in the 15-certificate film - should not have been exposed to scenes in which she had to gun down gangsters and skewer drug dealers with samurai swords, but the actress insists her mother was happy for her to take the part.

She told The Sun newspaper: "My mum reads every script before I go for it. She read it and loved the character because it was a challenging role and was something that would stretch me."

One thing the rising star wasn't prepared for, however, was the physical aspect of the movie as there was a lot of training involved.

She explained: "Two months before the movie started I started training to be Hit Girl. I didn't know it was going to be that physical. They made me do 1,000 crunches a night and like 50 pull-ups. I loved learning the martial arts moves."

'Kick-Ass' stars Aaron Johnson as the titular character and tells the tale of a comic book fan who decides he wants to become a superhero.