Seierstad entered Kabul with the Northern Alliance in November 2001. Like other western reporters exhausted by the privations and dust of battle, she was relieved to meet Shah Mohammad Rais, a bookseller who regaled her with stories of book-burnings under the communists, the mujahideen, the Taliban, of the thousands of volumes he had hidden, of his hopes for a liberal, democratic Afghanistan. He invited her to dinner, and she was struck by a simple idea: could she come and live with him for a few months, so she could see what Afghanistan was really like, and write a book about it? He told her she was welcome.
The result was not quite what either of them had expected: she was shocked by the treatment his female relatives received, and by the cruel lengths to which Rais went to protect his business. When Rais - thinly disguised as the character Sultan Khan - read it, he felt so furiously betrayed that he flew to Norway, engaged a high-profile lawyer, and threatened to sue for "defamation of me, my family and my nation".
None of this did Seierstad much harm: the book was already doing well, and the controversy simply aided its climb of the bestseller charts. It has been sold in 20 countries; there are a million copies in print. But Rais's reaction, so unusual in the history of western interpretations of the third world, prompts uncomfortable questions. To what extent is the book's success due to the fact that it plays on preconceived ideas of Afghanistan? Does a western woman, privileged, glamorous, have the right to hold a third world family up to her own values and find it wanting? Is it realistically possible to do anything else - there is, some argue, a kind of racism in simply saying, "Well, that's how they live, and who are we to judge?" If a thoughtful, essentially objective observer comes to these conclusions, what licence does it give to those less sympathetic and more powerful; those for whom the war on terror is also a war on values of which they disapprove?
It was the conflict in Chechnya that made Seierstad a war correspondent in the first place. After a degree in Russian and the history of philosophy (she speaks five languages fluently and has a working knowledge of another four), she moved to Russia, where she studied their great writers: Pushkin, Lemontov, Dostoevsky. "I was looking for the Russian soul," she says, without irony. "I loved Russia." She started to write features for a Norwegian paper, and when the war in Chechnya began in 1994 she decided to go and see what was happening for herself. Twenty-four years old, and "totally unprepared", she went to live with the guerrillas in the mountains, returning many times, against the wishes of her editor, and of her mother, who would call the newspaper, begging it to ground her. "I became anti-Russian - I thought, they're brutal, and they're drunk, and they're racist. Now I'm somewhere in between. But it hurts me still, the tragedy of the Chechen people."
She saw lots of fighting, lots of the "worst thing", killed and injured children; there are a couple of scenes in A Hundred and One Days, after the first American airstrikes on Baghdad, which are hard to read and she cried while writing. In one a young boy lies in the mortuary; his father and brother enter "and you can see the way they're walking, they don't know yet" - Seierstad has an expressive face, both girlish and steely, and even more expressive hands; "and then they see" - her hands sweep across her own torso - "half his body is away." The waiter chooses this moment to serve a bowl of soup, and a tuna niçoise - but her eyes are turned inward, looking somewhere else altogether, remembering "just their expressions when they see". But even that was not as bad as the hospitals, full of those who wouldn't survive: "They have their children's eyes, asking, 'What's happened to me?'"
Although in some ways none of this is news, Seierstad's book is valuable for its focus on the ordinary Iraqis she encountered, their very personal humiliation. Two men, friends all their lives, stop speaking to each other because one, a Shia, welcomes the Americans, while the other, a Sunni, feels the invasion as if it were a personal insult: her translator, a middle-class woman who has grown up believing in Saddam's benevolence and power, knowing nothing of his cruelties, retreats into hurt and bewildered silence. Here Seierstad is a mostly unjudgmental witness to complex realities.
The question is, why did she not take this approach to The Bookseller of Kabul? One of the most worrying things about that book is that she removed herself completely; it reads like a novel, entering impertinently into the thoughts and feelings of the family; she acquires, by default, the authority of the omnipotent narrator - an omnipotent narrator, that is, with the unsettling problem of an appalled tone.
Everything that appears as thoughts, or conversation, Seierstad insists she was told: she doesn't speak Dari, but Khan, his eldest son Mansur, and his youngest sister Leila, spoke English. "The pity," says Seierstad, "is that I happened to come across a really dysfunctional family. There was so much quarrelling. But I didn't know that when I started. It had nothing to do with me. And he also betrayed me!" she adds fiercely. "He presented himself as this great liberal - and I was even thinking, 'Oh, this family is too liberal, but maybe they have some relatives in the country who are more traditional?' The question is, should I just write what he tells me, or should I write what I observe and what the other people tell me? He [Khan] wants to be a hero in the west, and he wants to be a hero in his own country - a patriarch following all the traditions. You can't have it all."
The answer to this, perhaps, is that it's not that calculated - both things can coexist. "What I learnt," she admits, "is maybe it's not possible for a western woman to write an honest account of an Afghan patriarch, one that he would like. Maybe our worlds are too far apart."
Seierstad does not duck any awkward questions; rather, she tackles them head-on. She is just getting going on this when her PR appears to drag her away; she has to be on air at the BBC in five minutes. She rises accommodatingly, but can't quite let the thought go. "We can't get rid of ourselves as journalists. I think it was important to write A Hundred and One Days because it shows how I work: these are my shortcomings, this is what I'm trying to do. So yeah," she laughs. "It's more honest."
· A Hundred and One Days is published by Virago, price £7.99.