My father was horrified

In her novel, the central male character, father to 15-year-old Kambili, is a rich businessman and patron of the poor - in Nigerian terms, a "Big Man". He owns a newspaper which wins an award from Amnesty International for fearless journalism at a time of violent political unrest and an incipient military coup.

But at home, Eugene Achike, a fanatical Catholic, turns into an aggressive and highly inventive bully who regularly takes his belt to Kambili and her younger brother Jaja, and who beats his wife so viciously she suffers several miscarriages.

Has Chimamanda ever witnessed or suffered domestic violence? "No, never," she says. "But it's universal, isn't it? I don't think the problem is any worse in Nigeria than it is in America or the UK. Of course, my own father was absolutely horrified by the character of Eugene, and rather worried that people would think it was based on him.

When he first read the book, he kept asking me where I had got Eugene from. But it's all fiction. My father is the gentlest of men."

In one particularly ghastly scene, Eugene makes his children stand in the bathtub while he pours boiling water straight from a kettle over their feet, to teach them "what you do to yourself when you walk into sin".

"Yes, that's really horrific, isn't it?" whispers Chimamanda. "When I wrote it, I started to worry that my imagination was very dark."

Chimamanda's family belong to the Igbo people, one of the main ethnic groupings in Nigeria, and her novel is smattered with Igbo words and phrases. In Igbo, Chimamanda means "My God will never fall".

In 1998 she was sent to the US to study, and is currently enrolled on a Creative Writing MA course at Johns Hopkins University, and teaches a freshman writing course to boost her scholarship grant - "But I'm not very good at being American," she says.

"It's that homesickness thing again, particularly in the winter when it's so cold."

Although she makes friends easily, she is coy about more intimate relationships, and would be quite lonely were it not for her sister, who lives in Connecticut.

"We speak every day on the phone in Igbo. I eat Nigerian food and I have my hair done at a Nigerian hairdressers. America is a place of convenience. When I'm not being very gracious, I say that it's a place of convenience with no soul. But it's also a place of amazing opportunities and possibilities."

Before she wrote Purple Hibiscus, she tried her hand at a novel set in America, the classic immigrant novel, now a genre in itself. "But it wasn't very good," she laughs, "so I put it away in a bottom drawer. I'm much better at writing about what I really know. You have to be true and real, and I can only be those things about Nigeria."

Some would say this is a very good thing, since Nigeria, the most populous country in Africa, has barely produced an internationally famous writer since the emergence in the Fifties and Sixties of the literary generation defined by Achebe and that other great statesman of African literature, Wole Soyinka.

Indeed, fiction is hardly published there at all. Books about Nigeria are virtually unobtainable in the country itself, and novelists have no choice but to look abroad.

"Until very recently, when people talked about Nigerian writing, they began and ended with Achebe and Soyinka. The talent has always been there, but not the publishers. People can only afford to produce and buy textbooks," says Chimamanda.

"But I think there is a new flowering of writing in Nigeria now, another wave of incredibly good Nigerian literature. It's still hard to lay your hands on, but it's being done." Two years ago, she says by way of illustration, her Nigerian friend Helon Habila won the Caine Prize, Africa's version of the Booker.

Chimamanda herself offers only one piece of advice to aspiring African novelists: "Do not copy John Grisham. Write our own stories."

She is now working on her second novel, set during the civil war of 1967-70. Then, Biafra, the region from which Chimamanda comes, declared itself independent. During this time Wole Soyinka was arrested by the government and held in solitary confinement for two years.

She is far too young to remember the war, but her parents tell her about it. "My brother Chuks was born during it. As soon as my mother had given birth, the nurses at the hospital told her to wrap him up and take him home because they couldn't be sure that it was safe. The next day the hospital roof was blown off.

"People are afraid of talking about Biafra in Nigeria now, and generations are growing up not knowing anything about the war at all. I think that's wrong, and I'm hoping my new book will perhaps educate the younger people a little."

It's giving nothing away to say that Purple Hibiscus, whose sudden attention means its publishers are now reprinting, does not end in a Happy Ever After.

Adichie's prose is at times romantic and nostalgic, but the events she describes are not. It's a measure of her talent that the book she wrote as a cure for homesickness is never cloying or sentimental. Indeed, she squares up to Nigeria's problems with remarkable clarity.

"I take my next trip home next month," she says, "and I can't wait. I go back as often as I can afford to."

Intense, extremely clever and absolutely committed to African writing, Chimamanda Adichie is a debut novelist worth watching.

Purple Hibiscus is published by Fourth Estate, price £12.99.