Admittedly, dressing like a movie star probably doesn't help when it comes to preserving your anonymity. It's 11.45am when we meet, and the Swedish actress looks ready for the red carpet. Wearing platform heels and a charcoal black evening dress, with a thigh-flashing split, her long brown hair is elaborately pinned up at the back of her head. She couldn't look more different from the pierced and tattooed tomboy Salander, who prefers hooded tops to haute couture. But then, after a year-and-a-half of inhabiting her skin, Rapace is relieved to escape.

After shooting The Girl with the Dragon Tattoo and its two sequels (The Girl Who Played with Fire and The Girl Who Kicked the Hornets' Nest) virtually back-to-back, Rapace now visibly shudders at the thought of just how tough it has been to live with Salander for so long. 'As it went on, I was almost drowning in loneliness. I was in some kind of bubble,' she says.

'I felt like I was going to drown. Like 'I have to get out soon!' I'm never sick, but when we finished, I started to throw up. The producers came with a big bottle of champagne and everybody was celebrating, that it was the last day and last scene. And I just ran to the toilet, and I was throwing up. I was just lying on the floor for one hour.'

Her transformation into Salander was all consuming. She cut her hair, had real piercings and put herself on a strict diet - ditching the carbs and alcohol in favour of protein and vegetables. Desperate to shoot the film's fight scenes without resorting to a stunt double, she toughened her feminine frame with bouts of kickboxing. 'I wanted to be more like a boy in my body,' she says. 'Lisbeth's athletic, she's anorexic, but she can fight. She's almost cartoonish, like a female action hero. I wanted to humanise her. I wanted to wake up some kind of aggression in my body.'

If this sounds like fighting talk from Rapace, it was also an act of self-preservation, particularly given the harrowing nature of the material in the first part of the trilogy. While the core dynamic in Dragon Tattoo stems from Salander's relationship with disgraced journalist Mikael Blomkvist (played by Michael Nyqvist), who hires her to help him investigate a missing person case, the most memorable moment comes when the orphaned Salander is raped by her new guardian (Peter Andersson). A shocking event that will resonate through the trilogy, Rapace admits it was horrific to film.

'I was so exhausted by the end. I couldn't think. I couldn't talk. I was supposed to call home when I was in the car, just to let them know that I was arriving. But I couldn't say anything. I remember I took up my phone and I dialled my husband [Swedish actor Ola Rapace, with whom she has a six-year-old son] and I was crying. He said, 'OK, what's going on?' And I said, 'I'm coming!' And I hung up. It was like I'd used everything that was inside.'

It didn't help that she then had to shoot Salander's equally violent payback. 'It was like we were in hell for one week.'

Open and outgoing, Rapace is little like the antisocial loner Salander in the flesh. Yet, with a Swedish mother and Spanish father, she can relate to Salander's feelings of isolation. 'I always felt like an outsider somehow. I don't know what it is. Maybe it's just about energy, but I always felt that my energy doesn't really fit in with the Swedish mentality. In Sweden, everything is a bit lukewarm. Nobody wants to argue. Nobody wants to be too happy or too sad or too emotional. Everybody is trying to find a balance so they can be neutral.'

There's nothing lukewarm about Rapace, defiant when it comes to the question of reprising Salander for the Hollywood remake of The Girl with the Dragon Tattoo, due to start shooting this autumn in Sweden with David Fincher at the helm. 'I have been very clear that I don't want to do it again. I'm done. I'm finished. I can't see any reason for doing it again. It would be cynical. Like why - why do it in the American way? So I said it from the beginning, I'm done. I want to move on.'

This Rapace has done - having just signed on for the sequel to Guy Ritchie's Sherlock Holmes - but she maintains working for the US studios is not something she hankers for. 'I don't have this dream about Hollywood. It's not like I want to be a big Hollywood star. I only want to work. I don't care if it's a small independent film from the UK, or a Japanese film with no money. I don't really care - as long as it hits you. I think you always have to find something that you can't let go.' Whether she'll ever again find a role as gripping as Lisbeth Salander, however, is another matter.

The Girl with the Dragon Tattoo opens on Oct 14; The Girl Who Played with Fire opens on Dec 2; The Girl Who Kicked the Hornets' Nest opens on Jan 13