Lars von Trier: Anti-American? Me?

I ask about the politics of his recent films. "Oh shit! That sounds dangerous... The political part of my work, it's nothing I'm proud of. But it had to be there. I started at a time when everybody was very political, and the only justification for a film was if it had some kind of a political message. But I was very much into 'art for art's sake'."

Manderlay, the latest chapter in Von Trier's USA: Land of Opportunities trilogy, doesn't disappoint. Like Dogville, starring Nicole Kidman, Manderlay features the character of Grace - played now by Bryce Dallas Howard - and its stark, prop-less neo-Brechtian set is mostly drawn in chalk on a sound-stage floor, reminiscent of actors' marks. It's a Depression-era tale of slavery and racism in America's Deep South.

Having left Dogville ablaze, Grace and her gangster father (Willem Dafoe) find themselves at Manderlay, a decrepit cotton plantation where, 70 years after abolition, black workers are still bonded in slavery. The plantation owner, Mam (Lauren Bacall), begs Grace to destroy Mam's Law, the book of rules that govern Manderlay. Grace stays on to democratise the slaves, but chaos chases order. Wilhelm (Danny Glover) has seen this coming: "I fear that the humiliations this country has up its sleeve for us free coloured folks will surpass everybody's imagination. So, we voted on it, and agreed we'd like to take a step backwards at Manderlay and reimpose the old law."

In America, Manderlay was considered so inflammatory that few black actors would go near it. Glover initially turned it down, but reconsidered. That said, publicity material claims that Manderlay is a metaphor for President Bush's aggressive interventions in Iraq: Grace cannot understand how her compassionate imposition of democracy turns into dictatorial severity, and Manderlay's slaves demand their own oppression, preferring the certainty of captivity. "Every other system of government is easier to enforce than democracy," Von Trier says.

The director has retreated somewhat from the claim that the film is an allegory of American intervention. "It's not necessarily about Bush. You can see the film like that, but it was written before Iraq. But why make a film that would do just that? I would never make a film like that."

His "USA" films have incited reproachful accusations of pinko anti-Americanism. The end credits to Dogville and Manderlay exhibit a montage of photographs by Dorothea Lange and Jacob Holdt of social deprivation in America (set, rather histrionically, to Bowie's "Young Americans"), which emphasise that economic inequality results from a coldly rational exploitation of need.

Are Dogville and Manderlay straightforwardly anti-American? Von Trier sighs: "I don't know. That would make all films that have gangsters in them anti-American. You are right in saying that, of course, the deeper conflicts in the films are not especially American. They are from right where you are yourself."

Grace is a kind of allegorical refugee whose desperation and need for protection leave her defenceless against exploitation. "Being an immigrant or a refugee was very important in my family," Von Trier says. "My father and my mother both escaped to Sweden during the Second World War in a life-or-death situation. So, the whole issue of what you do with people who come to you fleeing from somewhere bad has always been important in my family."

At this point, Zentropa boss Aalbaek-Jensen dives into the pool, splashing us. "Why does he have to do that while we sit here!" scowls Von Trier. "This is my producer. He keeps in the background, as you can see. But now he has succeeded in making us completely aware of his presence." One could not fail to notice Aalbaek-Jensen; he's naked.

"If something can actually be said about politics in my films," von Trier resumes, "I would say, 'It's nothing I am proud of.' But I don't think that there is such a big difference in the films now from what I've done earlier." He is referring to his re-released E Trilogy of The Element of Crime, Epidemic and Europa, which all use hypnotic and hysterical devices to expel the repressed memories that dog European history. "All I can say is that my technique is to go where it hurts, somehow," he says, "and, of course, that goes for memories and history. I see things through my upbringing as a left-wing, cultural-radical humanist. What I have tried in all my films, also the old ones, is to challenge myself and my beliefs. That's the technique."

No one could accuse Von Trier of being antisentimental - the emotional wreckage of Breaking the Waves, The Idiots and Dancer in the Dark devastated most audiences. Something like a compromise between these extremes is reached in the neo-Brechtian sparseness of the USA trilogy. Yet his fixation with pain and suffering persists.

"Manderlay is actually based on the prologue to The Story of 'O'," he says. "Pauline Réage's lover, Jean Paulhan, was a member of the French Academy of writers or whatever, and he wrote a preface to The Story of 'O' about slavery; the human lust for slavery. The story he told was about slaves who were freed by law in the Caribbean. Because they had no food or anything, they went back to the slave owner and wanted to be slaves again. The owner said, 'No, I can't do that or I will go to jail.' And so they killed him. I thought this quite an interesting story. I'm sure that masochism, as well as sadism, is at the heart of all our psychologies. This story about the freed slaves - that was the inspiration for Manderlay."

Published under the pseudonym Pauline Réage, Dominique Aury's S&M classic has been filmed by avant-garde luminaries such as Kenneth Anger, and Von Trier regular Udo Kier starred in Just Jaeckin's film adaptation. In 1979, a young Von Trier and the film co-op Film Groupe 16 shot his own short black-and-white version called Menthe - la bienheureuse. "Many years ago, I made this little something before I went to the Danish Film School," he says. Sadly not yet included on a Von Trier DVD release as an extra, it is, as expected, a naive if promising student film, pretentious but surprisingly unpornographic.

Von Trier likes to expose the processes and politics of film-making, most notably with the playfully nostalgic avant-garde movement Dogme 95 and, more recently, with The Five Obstructions, a documentary about the ethics of film art. In its portrayal of a pseudo-political commune who épater le bourgeois by pretending to be mentally disabled, his Dogme film The Idiots satirised melancholically ineffective modern radicals.

Von Trier himself is an advocate of collectivisation, yet recoils from the herd, shielding his auteur status to retain total creative control. "It's the same as the problem of democracy," he protests. "Eighty per cent of Danes are too stupid for democracy, right? Because they think something else, or because they don't agree with me!"

In the run-up to Denmark's 2001 election, he placed full-page newspaper ads petitioning the electorate to vote against the far-right Danish People's Party. "I would love to work in a community," he sighs, "but I haven't found others that would be stupid enough to do what I think is right. The will for the collective ideal - nobody really seems to have it these days."

This year marked the 10th anniversary of Dogme 95, and the movement was officially closed down. Ever the rebel, Von Trier immediately planned a new Dogme film called Managing Director of It All. "It will be made from the technical Dogme rules, but it will not have a certificate because it does not live up to the other side of Dogme - the intentions of the content of the films. After making Manderlay, I needed a little break. Lock me up in a cell for two months so I can have some vacation! I needed to do something to have a good time, something not too ambitious."

Speaking of ambition, Von Trier almost single-handedly revived the Danish film industry, despite mostly shooting films in English and with foreign actors. He can now attract American stars such as Bacall, Kidman, James Caan, Dafoe, Glover and Ben Gazzara, not to mention European idols Catherine Deneuve and Björk. "Some of these stars have their own games," he laughs. "You ask them and, strangely enough, some of them say yes. With a female actor, I think that they think I can do some good for them in terms of their career." Surely Hollywood divas are not queuing up to be shackled, gang-raped and offed in another of Von Trier's "martyrdom of the innocent" scenarios? That said, Kidman's performance as Grace in Dogville was arguably her best so far, although she declined to sign up for the second instalment.

Is it the impression of vulnerability that attracts him time and again to marginal characters like romantic idealists, immigrants and people with mental illnesses and disabilities? "With the foreigners, and also the idiots, it's that they are spices, somehow, to our lives," Von Trier replies. "They are not necessary. Maybe you could say they are necessary for the moral life of the country, but they are not necessary to the state. I would hate to go around in a country where there were no foreigners whatsoever. That would be really scary.

"And outsiders are attractive to anybody. They are attractive just for entertainment value. What we have displayed in circuses are foreigners and idiots, right? That's more or less what circus is about; to put them on display. Well, maybe there's a tiger in between them, or whatever. Oh, and then there are skills, you can also show skills in your circus..."

Something of a circus is going on at Zentropa. Aalbaek-Jensen is parading naked again, and Von Trier rebukes him: "Peter! Could you put on some clothes please?" Aalbaek-Jensen crossly retorts that he's "not trying to shock anybody".

Von Trier once said that "a film should be like a stone in your shoe", meaning that it should provoke. Does he prefer that his films remain difficult and opaque? "Oh yes, absolutely. I would prefer that!" He nods enthusiastically, as his PDA beeps. "Sorry, I have to go to my yoga class now..." He bows, clasping his hands in prayer and offering a peaceful "Prana".

'Manderlay' is showing at the BFI London Film Festival, 23 and 25 October (020-7928 3232); it goes on general release next year