Imre Kertész was sent to Auschwitz as a child, and his controversial novel based on his life there has been made into a movie. The Nobel Prize-winning writer talks to Julian Evans

'For whom do we write?" asked Jean-Paul Sartre in his 1947 manifesto, Qu'est-ce que la littérature? (What is Literature?), a question of intellectual urgency in a smashed and impoverished Europe. "The universal reader" was a shattered category, and the writer himself, in Sartre's words, knew "he speaks for freedoms which are swallowed up, masked, and unavailable". The writer's own freedom, too, "is not so pure; he has to clean it".

Imre Kertész bears witness to the arduousness of this process of self-authentication.

"I had to establish my independence, my mental independence," he says. "I came from two harsh dictatorships, Nazi and Stalinist. I never thought of becoming a writer as such, yet in a lucid moment I recognised what I had to do."

His first novel, Fatelessness, which grew out of his experiences as a boy in Auschwitz and Buchenwald, did not appear until 1975. There is a good reason for the long delay from lucid moment to authorship. Europe's 20th-century totalitarianisms, of which Auschwitz was "the ultimate embodiment", created a new kind of humanity, he says. "They forced a person to choose in a way we were never forced to choose before: to become either a victim or a perpetrator. Even surviving involved collaboration, compromises."

To choose to become a writer was his way of refusing to collaborate with dictatorship.

Born in November 1929 into a Hungarian-Jewish family, Kertész was deported from Budapest at 14. At the first selection, he lied about his age and called himself "worker" rather than "schoolboy" to appear more useful to camp officials, and survived. He was liberated by American troops a year later, though by a quirk of Nazi record-keeping, the Buchenwald register notes the death on February 18th 1945 of "prisoner 64921, Imre Kertész". "I died once, so I could live. Perhaps that is my real story," he said in his 2002 Nobel prize lecture.

He does not discuss the details of his adaptation to peacetime and adulthood. He has the profound charm and good humour of those who have seen life at its vilest and most absurd, but the disturbed pattern of his early years is painfully clear. Having found his life again, he felt he was losing it.

"To my horror, I realised that 10 years after I had returned from the Nazi camps . . . all that remained of the experience were a few muddled impressions, a few anecdotes," he says.

From 1948 he worked for a Budapest newspaper, Világosság, only to be sacked in 1951 when it took the Party line. He then had two years of military service. Mentally, he was adrift.

"What happened was that I got so deeply involved in these dictatorships, I was beginning to get lost in them," he says. "First, I had to recognise that I was stepping out of line, out of line with the masses."

He began to write "pieces of text and then more pieces of text. This was not the novel as you know it, but I tried to create a summary or a description of dictatorship". Suddenly, "on a lovely spring day in 1955", he realised there was only one reality, himself, his own life, "this fragile gift bestowed for an uncertain time, which had been seized, expropriated by alien forces . . . and which I had to take back from 'history', this dreadful Moloch, because it was mine and mine alone".

Finding himself against everything that communist Hungary stood for, he started Fatelessness. Its central proposition was that we are our own fate, connected to every event we make happen and that happens to us: "If there is such a thing as freedom, then there is no fate."

He is sure he would not have written about the Nazi dictatorship "had I not known the Stalinist dictatorship and the Kádár dictatorship [ of post-1956 Hungary]. It was a bit like Proust's madeleine - a real revelation". An advantage of conditions in Hungary was that "all the circumstances were there for you to become a crypto-writer, a hidden writer, because it was a cheap way of life, the outgoings were low, the cost of maintenance was low, there were no status symbols to wish for, and it was a reduced way of life and you could concentrate on your work".

In the intellectual desert of the Stalinist era, he read a great deal. He had his first experience of the power of literature before his deportation, when at 13 he read CS Forester's Captain Hornblower RN.

"I'm still wondering how it was possible to publish it in the middle of the war . . . Captain Hornblower [ was] a hero I had never seen before: he was weak, he had doubts in himself, he was concerned, and he won every battle," he says. "And you had to be very stupid not to see that the usurper Napoleon in this case was really Hitler."

In the summer of 1957 he discovered Camus's L'Étranger:

"At the time it was simply unimaginable to me that it was possible to write like that," he says. "I was looking for a cheap and interesting book and I'd never heard the name before. And it cost only 12 [ Hungarian] forints! So I took it home, and that became my destiny."

L'Étranger and Death in Venice showed him what radical literature was. Later there was Flaubert, Dostoevsky ("the first and most beautiful novel about a camp is The House of the Dead") and Ford Madox Ford (he's read The Good Soldier 11 times). He supported himself by translating Nietzsche, Freud, Kafka, Joseph Roth, Wittgenstein and Canetti.

When Fatelessness was finally done, he submitted it to the more liberal of socialist Hungary's two fiction publishers. It came back with a rejection letter, so he sent it to the other, "more cowardly" publisher. Two readers wrote positive reports, which meant automatic publication. He finally had his answer to the question of who he wrote for: himself. The novel was received in almost complete silence, viewed as a cynical provocation, a book about the Holocaust that refused to wear the accepted robe of victimhood; it declared everyone, perpetrators and victims, had taken their own steps towards their future. Gyuri, Kertész's hero, tries to explain this to his surviving uncles when he returns to Budapest:

"What!" he bawled, his face red as a beetroot and beating his chest with his fist. "So it's us who're the guilty ones, is it? Us, the victims!" I tried explaining that it wasn't a crime; all that was needed was to admit it, meekly, simply, merely as a matter of reason, a point of honour, if I might put it that way."

Narrating in a constant present, Gyuri has no hindsight; every event is new, interpreted by an adolescent personality who enjoys adventures, is easily bored, likes change. Ordered off the bus in Budapest, his thought on learning that he is being sent to work in Germany is that he'll find "orderliness, employment, new impressions, and a bit of fun - all in all, a more sensible lifestyle". He has not heard of Auschwitz. He notes that the sunrise at the railhead is "pretty and, on the whole, intriguing: back home, I was usually still asleep at this time". When he becomes aware that his fellow passengers from the train are burning, he is "well aware that it was not altogether a joke", but his imagination is taken up with how this "fantasy" became a reality, through the ideas of "gentlemen in imposing suits, decorations on their chests".

Through this demanding formal device, Kertész offers Gyuri's experience as entirely fresh. To see the Auschwitz of 60 years ago through Gyuri's eyes is to feel an overwhelming sensation that it is happening now, the result of brick-by-brick, step-by-step cooperation between perpetrator and victim - as, of course, genocides are still carried out today.

"[ I wanted] to write a scandalous book, a scandalous piece of text, something that had never been written about before," Kertész says. He succeeded.

Fatelessness, a marvellous, radioactive piece of storytelling, became the first of a trilogy. The second, Fiasco (1988), dealt with his critics' silence, and Kaddish for an Unborn Child (1990) brought Gyuri back to speak about the child he refuses to have in a world that allows Auschwitz to exist. He has written two volumes of a fictional diary and three collections of lectures and essays - but when he became the 2002 Nobel laureate it was for an unusually compact body of work. Astonishingly, Fatelessness was not published in Britain until 2005, and remains his only work available there. A fourth novel, Liquidation (2003), is out in English this year, and Kaddish is obtainable in a US edition - a bizarrely small presence for a writer of world stature.

Perhaps the original difficulty remains. There is no getting away from Auschwitz in his work, and what he wishes to say about it is too provocative for general consumption. To his mind, Auschwitz is the culminating point of western civilisation.

"What I have discovered is that Auschwitz was an absolute moment in the history of Europe, intellectually," he says. "Maybe it sounds strange that I call this awful atrocity, which killed millions of people, part of an intellectual activity, but allow me to be a cynic . . . The traditional values have burnt out, have been emptied, and I cannot yet see the creativity which could create new values."

Derived from this is the proposition in Fatelessness that it is evil, not good, that is explicable: evil is simply the result of making decisions, whereas good has no logic to it. And, post-Auschwitz, good is still out of the ordinary.

"Modern life is organised so that you benefit at the expense of the other, and the most extreme example of that is a camp," he says.

Does he mean Auschwitz and capitalism are parts of a single philosophy? He is not sure. But "it's the organisational structure of life, and I can't see a cathartic event that would bring us out of this pattern and make people live or behave differently. The catharsis that such an event could have evoked didn't happen. Everybody can only write about Auschwitz, even if Auschwitz as such is not present in the work. It is so decisive. Beckett never mentions Auschwitz, but his world is ultimately derelict. And one cannot get rid of this. The work of Giacometti, for example, or the latest modern music. We are after something. That's the way we live. What writers can do in this symbolic ice age is to preserve and present individual identities, individual existences that you can pick out from the flow and present as something that moves people, or shocks them."

We now live in a state of such conformity that we are in danger of forgetting those existences? "Exactly."

Fateless, the film adaptation of Imre Kertész's novel, opens on Friday. The screenplay is by Kertész, and it is the directorial debut of Oscar-nominated cinematographer Lajos Koltai (Mephisto, Being Julia). Marcell Nagy plays the lead character and Daniel Craig plays the US soldier who liberates him from Buchenwald