Emmanuelle Béart: 'Sometimes you feel more naked when you're totally dressed than the other way round'

Were you ever to need reminding of the effect Emmanuelle Béart has on men, you'd do well to recall the time she appeared on the cover of French Elle magazine, in 2003. With the actress pictured naked on a Mauritian beach, Frenchmen flocked in their droves to their nearest news-stand. The entire print-run of 550,000 copies sold out in just three days, making it the biggest-selling issue in the fashion glossy's long history. For Béart, the explanation was simple: "It was to say, 'Look, I'm 40, this is my body, these are my curves, I like them and I'm proud of them.'"

This was not Béart's first public appearance unclothed. At 23, she came to the world's attention as the enigmatic mountain girl in Claude Berri's much-loved Manon des Sources, skipping through the woods as nature intended. Five years later, in Jacques Rivette's acclaimed 1991 film La Belle Noiseuse, she barely kept a stitch on – and sometimes not that – playing a model posing for a great artist. "It's wasn't my ass I was exposing," she noted at the time. "It was my soul." But after two decades in the public eye, there's little to suggest that Gallic gentlemen – and a surprising number of Gallic ladies too – are any less entranced by a performer they regard as nothing less than a national treasure.

A tabloid paper may have suggested last year that her trademark lips were suffering from a Lesley Ash-style "trout pout", but in person the baby-blue-eyed Béart is still a beauty at 45. Today, with her famous curves concealed beneath a full-length dress, patterned with green, blue, black and purple swirls, and with her toenails painted to match her long dark hair, she looks as elegant as the thin cigarette she fishes out of her purple patent handbag.

Béart – who once stated that she went very far in destroying her face on screen – has always had an ambiguous relationship with her looks, however. Note the time, in 1997, when she marched against France's right-wing government to protest against legislation that decreed that landlords must declare foreign lodgers. This activism, aside from attracting death threats to her, left one employer – Christian Dior – less than impressed. Seen on the demo with unbrushed hair and sporting a scruffy raincoat, she was criticised in the French media for neglecting her image. "My looks mean nothing to me," she retorted. "If anything, they are a hindrance."

From her politics to her acting parts, Béart has certainly become more provocative as she has grown older. Take her role in Nathalie, the hard-hitting 2004 release in which she played a prostitute hired by a woman to seduce her husband. Béart denies, however, that she's compelled to play sexually motivated characters just for the sake of it. Or that she does nudity at the drop of a hat. "Usually, there's really a reason. I don't give my body to everybody," she protests. "But I've never said it was a problem. On the contrary, it's a source of creativity. Sometimes you feel more naked when you're totally dressed than the other way around."

Still, nothing in her CV compares to her role in Vinyan, the visceral new English-language drama in which she stars with Rufus Sewell. They play a couple who lose their son in the 2004 Indian Ocean tsunami, which claimed the lives of 225,000 people in 11 countries. Refusing to believe he's dead, their search takes them into the jungles of Burma and towards their very own heart of darkness. Directed by the Belgian film-maker Fabrice Du Welz, who made the riotously perverse 2004 horror Calvaire, the film draws a great deal from Apocalypse Now, with its depiction of madness in the mangroves, but it does so with the greatest respect.

Not that any such artistic considerations matter one bit to those who really did lose friends and relatives in the tsunami. When the film premiered in Venice last autumn, it immediately drew criticism for using the tragedy as a backdrop to the story. Béart remains unapologetic: "What can I say? We're not using the tsunami. We're just talking about a couple who lost their son. It's in the tsunami but the important thing was that Fabrice wanted a different culture ... and Asia is a very different culture. What can I say? I do respect their sorrow but they have to respect the work of Fabrice. I have nothing to say to that. It's so far away from what we thought."

Maybe so, but Béart has little explanation for the film's final scene, in which we find her character, Jeanne, naked, caked in mud and surrounded by cannibal children – who slide their hands over her torso, limbs, even breasts. A shocking finale by any standards, "it has to be seen to be believed", as Variety put it. Again, Béart is unrepentent, believing the scene to be one of beauty. For her, Vinyan – which means "evil spirit" in Thai – is about much more than earthly flesh. "In our society, death is the end, death is something we can't deal with. But when you go there, you are in a culture where death is a continuation of life. It's like life after life."

Whatever you think of the morality of using the tsunami as a backdrop for a supernatural horror story, there's no doubt that a transcendent Béart gives her all in one of her most startling performances in years. It's all the more impressive when you consider that the filming conditions were less than glamorous. "Every day, I was just saying to myself, 'Be brave! Go out! You can't get sick. You can't.' You don't heal there. Every time a member of the crew got ill, they just couldn't go on." During the shoot, she picked up an ear infection that meant she couldn't hear properly for much of the time, but she struggled on. "I was talking to myself a lot," she admits.

Béart claims she's well-equipped to deal with such hardships, having worked with Unicef, visiting "very difficult countries", for 10 years from the mid-1990s. "I know what to eat and drink, I know how to protect myself," she says. Among these difficult countries were Sierra Leone, where she watched efforts to demobilise and re-educate children who fought in the country's civil war, and Vietnam, where she helped inaugurate a credit system enabling women to become self-sufficient. So what made her stop? "The real reason was ... being a witness for 10 years. I had the impression I had to pass it on to someone else, the job. It was healthier."

Béart may have had a desire, too, to spend more time with her children, now they've reached the troublesome teens. Her daughter, 17-year-old Nelly, comes from her 10-year relationship with actor Daniel Auteuil, whom she met on 1985's L'Amour en Douce. After starring together in the art-house hits Manon des Sources and Un Cœur en Hiver, she and Auteuil married for two years, before divorcing in 1995. She then struck up a relationship with composer David Moreau, giving birth to a son, Johan, now 13, before they too split.

Last August, she wed the actor Michaël Cohen, who is seven years her junior – though getting her to talk about it is another matter. "I'm protecting myself," she says. "I'm trying my best to keep my private life guarded. It's not easy at all. Non, non, non..." With her final words switching from English to French – a trick she pulls regularly when she wants to hide behind the language barrier – she almost wags her finger to warn me from getting any closer. In truth, though, such reticence is understandable. Fame has been a constant torment to her – and not only because her love life has been such a long-running source of fascination for the French media.

Her father is the noted ballad-singer Guy Béart while her mother is Genevieve Galea, a former model and one-time muse to Jean-Luc Godard. The pair separated nine months after Béart's birth, and she grew up with her mother, three brothers and a sister on a farm in the Midi, harbouring no greater ambition than to be a drum majorette. But her father's celebrity was something that would never sit easily. "I hated it," she shrugs, recalling how she loathed fans approaching him in the street. Doubtless this helped brew her rebellious streak: she was expelled from five schools, before, at 16, being shipped off to Montreal to learn English. Spotted there by the great Robert Altman, she was cast in a project that never came to fruition, but returned to France to study acting.

Over the years, Béart has developed a reputation as a perfectionist – from spending 18 months learning the violin for Un Cœur en Hiver to prowling Parisian bars in search of prostitutes on which to model her character in Nathalie. In all this time, her English-language roles have been infrequent and – at least until Vinyan – unsatisfying. Most famously, she played Tom Cruise's squeeze in 1996's Mission: Impossible. Has she kept in touch with Cruise? She shakes her head. "I have no TV, thank God," she explains. "I haven't heard anything about Tom Cruise, except that he had a baby, I think."

In 2006, she co-starred with Harvey Keitel in the little-seen thriller A Crime, but seems to have no desire to forge a Hollywood career. "I get many offers, which is weird because I don't even have an agent there. After Mission: Impossible ... it came like a machine gun, one after the other – all the exotic women – for a while." So why did she refuse so many offers? "I was not interested. I would rather do Polish, Russian, Greek ... it's not important for me where it comes from. It's the director, the way he wants to tell a story. That's the very important thing."

Since Vinyan, Béart has completed Mes Stars et Moi, reuniting her with Catherine Deneuve, with whom she co-starred in the critically acclaimed 8 Women in 2002. Béart plays a star being stalked by a fan, something she's experienced for real. "Usually, I see it and I stop it. I say, 'C'mon. Let's have a coffee.' One of them really became a friend. I said, 'You're going to stay there for hours, freezing cold. Come in the trailer and we have a coffee. Tell me where you come from.' And he was like, 'No, no, no thank you!' I said, 'If you don't, I call the police.' So he came in my trailer and he's a friend now. A real friend."

While attracting stalkers must be a common hazard for Béart, given the effect we know she has on men, inviting them in for coffee might seem a risk. But this is typical of her disarming nature. Like the time she chained herself to the railings of a church to highlight the plight of immigrant workers, she does as she sees fit, on film or in real life. "I'm a citizen!" she cries, pointing out that it's her duty to be socially aware. "I think it's our present but it's also the future – mine and my children's. I don't see why being an actress would stop you from being a citizen. I'm a woman before being an actress."

'Vinyan' screens tomorrow night at the Edinburgh Film Festival and goes on general release on 18 September