"Italy, 250. Brazil, 210 . . ." No, it's not a soccer result. Nor is it some kind of surreal exchange rate mechanism or a global weather forecast. It is the sound of Paulo Coelho attempting to calculate how many books he has sold worldwide by adding current print runs to his July sales figures. "Portugal, seven, hmm. . . I think that we may be close to 31. Yes." He looks up and beams like a man who has just discovered the meaning of life. "Yes, 31 million." That, folks, is an awful lot of books. Only John Grisham has sold more. But where people read Grisham for escape or amusement, they appear to turn to the Brazilian novelist for a very different kind of reading experience. Take his most recent book. It's called Veronika Decides To Die - and the title isn't kidding. The opening paragraphs see the heroine proceeding, calmly and methodically and not before brushing her teeth, to commit suicide. At the end of the first chapter, she loses consciousness. She doesn't die, but when she comes around, it is to discover that a) she is in a mental hospital, and b) the suicide attempt has damaged her heart so badly that she has just five days to live. If there are laughs in Veronika, they're the black kind. In fact, Coelho's combination of lunatic plot and pared-down, po-faced prose produces a tone that might best be described as Borges meets Blackadder. Not too surprising, then, that he cites Borges as inspirational, along with Henry Miller and Carlos Castaneda. Can he remember when he first read the Argentinean alchemist? He grins delightedly. "It was in a science fiction anthology. I used to read a lot of science fiction. I arrived at this fantastic story called "The Library of Babel" and I thought - Jorge Luis Borges? Who's he? I thought he was a science fiction writer. So I started tracking him. The next book I read was Fictions; and I loved him. It was only later that I discovered he was born the same day as I was born. So every time that I used to celebrate my birthday I used to raise a toast to Borges . . ." The Coelho who zooms around the world promoting his slim little bestsellers is a devout Catholic who prays and reads the Bible daily. He has come to Ireland to make a television documentary about the Cappoquin women who saw visions of the Virgin Mary. Why would one of the world's wealthiest writers agree to make a documentary for a small independent Irish film company? Because it was in his destiny, he says, without batting an eyelid. To his legions of fans, he is the man who has discovered the meaning of life - and then passed it on in the shape of The Alchemist, his megaselling volume about a Spanish shepherd boy who travels to the pyramids in search of his destiny - but he hates to be filed under "new age" or "self-help". "I'm not trying to convince anyone of anything," he says. "I'm just sharing my experiences." When readers come up to him, though, and say - as they must - "your books have changed my life", is that satisfying, or scary? He looks dubious. "They may say that to me, but not in the sense that they say `your book has changed my life and now you have a responsibility'. They say that, and I understand that he or she was strong enough to change his or her own life - they only needed proof that they are not alone. I never got a letter or phone call saying `oh, you changed my life and now I'm worse than ever', you know? I always got this kind of sense that we are companions on the same journey."

Few of us, in truth, are on a journey even remotely comparable to Coelho's. As a fictional storyline, his life would make Grisham blench. During his teens he was committed to a mental hospital by his parents, who feared his expressed desire to become an artist in a Brazil under military dictatorship was tantamount to lunacy. After his eventual release - he escaped twice, and was promptly returned - he established himself as a songwriter and penned a string of rock hits. At the age of 26 he was arrested, tortured at gunpoint and held in captivity for two months. And here he is sitting in the bar of the Westbury Hotel, charming, unassuming, totally at ease in the English language - of which, a decade ago, he spoke not a word. He learned it in order to do interviews. By any standards, Coelho is a remarkable individual. His writing, however, has not - to put it mildly - received universal acclaim. There have been plenty of celebrity endorsements; President Bill Clinton, Madonna, Julia Roberts and, most recently, Sinead O'Connor have all sung his praises. But the critics have not always been kind. "Curiously conventional and even rather sentimental", was the Times's verdict on Veronika, while a writer in the Brazilian news magazine Veja dismissed his famous countryman's entire oeuvre with a crisp "I haven't read it, and I don't like it". But the simple, childlike tone which enrages the literary stylists is, he insists, absolutely intentional. Minimalist, even? "Minimalist. That's the correct word. I always liked that idea of minimalism, but without losing the poetic quality of the language. I try to be very, very direct. The first draft of the book, of course, is very, very thick - but then I start to cut and cut and cut, to give to my reader the possibility of using his or her imagination." It is pretty weird, though, to read Veronika Decides To Die, with its portrayal of life in a mental hospital as essentially nurturing and safe, and realise that it's based on direct experience. Was it not a painful book to write? He shakes his head. "I never saw myself as a victim," he says, slowly. "I. . . never saw myself as being tortured by my parents. But there are some things in your life that either destroy you or make you stronger. This made me stronger; and many people may be facing the same situation. Not the hospital part, but a struggle within the family, the necessity of fighting for your own space, you know. . .

"The only problem I had was with my father. But he received the thing very, very well. I think he always thought that the day people would discover I was committed to a mental institution, my career would be over; that people wouldn't believe in me any more and would think my books are crazy. But when I told him I was going to write this book, he said `OK - if you think this won't cause you any harm, it's OK for me'." And what about Doctor Igor, whose theory that unhappiness is caused by the presence in the human body of a toxic substance he calls "Vitriol", which has profound implications for Veronika? Is he by any chance based on the doctor who told the teenage Coelho to stop pretending to be crazy and get a life? The adult Coelho throws back his head and laughs. "No, he's not. But I remember writing the part about Vitriol, and when I'd finished I said to myself, `my God, this makes a lot of sense'. And I started reading that particular part to some friends of mine - and they said, `Did you read this in a psychology book?' I said `No. I just made it up'. . ."

Veronika Decides to Die is published by HarperCollins at £6.99 in UK. The documentary in which Paulo Coelho took part, Seven Days in the Summer, was made by Little Bird productions; it is due to be screened on RTE1 in autumn 2001