The Hollywood beauty - who plays Natasha Romanoff and her alter-ego, sexy Russian spy Black Widow - enjoyed working on the comic book adaptation because she filmed her own violent stunt scenes.

She said: "I'm kicking some major a*s - so I would say 'major' is the amount of a*s I kick.

"Whose a*s do I kick? Well, you're just going to have to wait and see. You don't really want to know, do you?"

Scarlett - who wears a high-tech tight black leather suit for the part - spent months training for the physical role.

Despite the hard work, the 24-year-old starlet says the physical sequences were her favourite scenes to film.

She explained: "Well I have to say I loved doing all my stunt sequences, because those are the ones I know best. I've got to fight for them. I've got to be my own cheerleader. So, all the Black Widow sequences, of course.

"Whose side is she fighting on? I don't know. I think you've just got to call me a super shape-shifter."Scarlett took on the part after British actress Emily Blunt dropped out earlier this year.

'Iron Man 2' - which also stars Robert Downey Jr., Gwyneth Paltrow and Mickey Rourke - is due for release in May next year.