When your name is Bin Ladin...

But she hasn't had much choice in the matter.

On September 11, 2001, Carmen was in Geneva with daughters Wafah, Najiah and Noor when she heard about the terror attacks. Like everyone, she was stunned by the human tragedy. But Carmen felt additional revulsion, because she immediately suspected her brother-in-law was involved.

She'd had had nothing to do with the huge Bin Laden family since becoming estranged from her husband Yeslam in the late 1980s. Indeed, the medieval ideology of Osama Bin Laden had come to ''exemplify everything that repelled me about Saudi Arabia'', she says.

But in the hysteria which followed 9/11, the name alone was enough to link her to him in the public mind. The 'i' she uses to spell Bin Ladin might have offered a clue that she was no ally of Osama's, but as the only member of the family in the European phone book, she and her daughters became the focus of huge media attention.

''It was very difficult for my family to carry the Bin Laden name,'' she says. ''There was an article about my eldest daughter, Wafah, who was studying law in New York and lived close to the Twin Towers, stating that she had been tipped off and flew out to Switzerland days before the attacks.''

In fact, she had been with her mother since the beginning of the summer, but the report was widely circulated and the prejudice stuck. Her flatmates began to receive hate calls, and job offers she had won were rapidly withdrawn.

In Geneva, Carmen was experiencing similar problems. Some friends urged her to change her name, but she decided it would look worse if it was revealed she was ''hiding'' the connection. ''So I decided that I had to explain to our world - the free world - where we stand, the four Western Bin Ladins,'' she says.

After issuing a statement condemning Osama and the attacks - something no other Bin Laden has yet done - she set to work writing an account of her life in the powerful Saudi family. Partly, this was to dissociate herself and her daughters from their notorious relation. But it was also for more personal reasons: she wanted to explain to her children how she had first come to marry into Saudi Arabia, and why she has struggled so long and hard to leave it.

''For the last 14 years, they have paid a very high price. When you see your father in the street and he doesn't say hello to you, you don't understand. They would ask me why? And I always told them, 'One day I will write you a book to explain to you why I felt it would be better for you not to grow up in Saudi Arabia'.''

The result, The Veiled Kingdom, opens a rare window onto a country which likes to keep itself to itself where the West is concerned, and insists that its women are neither seen nor heard.

Carmen herself, as an impressionable 23-year-old growing up in Geneva, knew very little about the country when her mother rented rooms to a tall, good-looking young Saudi.

Yeslam was one of 25 sons, and 29 daughters, born to Sheikh Mohamed Bin Laden, a construction mogul with very close ties to the Saudi royal family.

When the House of Saud began to harvest the country's enormous oil riches, the Bin Ladens grew rich with them, building hotels and offices for the international trade converging on the formerly backward desert kingdom.

''He was very clever, he had a real presence, and he was very interested in me. He would not address other people, but he talked to me, so I felt very special,'' remembers Carmen.

When he asked her to marry him soon after, she had little hesitation in saying yes. If she had some notion that she was marrying into a very strict Islamic culture, it was pretty abstract. ''If I tell you there are no movies, no music, no theatre, you hear what I say, but until you live it...''

Likewise it was only when she arrived in the country and felt herself disappear inside the full-length abaya veil that the reality of her new situation began to hit home.

Even then, she felt, things were changing. ''The country was changing so fast materially, it seemed inevitable that they would change morally, too.''

But it gradually began to sink in that life for Saudi women was not going to change any time soon. Women could not be seen out of the veil, they could not socialise with men other than their husband, and were expected to remain almost exclusively at home.

The rules, derived from the strict Wahhabi version of Islam which governed Saudi Arabia, were exemplified by the family life of her brother-in-law Osama, who was particularly respected for his austere piety. Carmen remembers his wife Najwah meekly allowing her baby to grow dehydrated one boiling hot day because her husband had decreed that bottles were un-Islamic, and she must feed him water with a spoon.

Although Yeslam had regular dealings with Osama, his pious avoidance of women meant that she saw him only three times in nine years.

''Once I was playing with Wafah near the front door and he knocked, calling for Yeslam,'' Carmen remembers. ''I opened the door wearing a T-shirt and jeans, and as soon as he saw me, he turned away, waving me frantically away with his back to me. I said, 'but Yeslam is here!', but he kept walking off until I went and hid myself away.''

Her husband's apparently 'westernised' style allowed her to win tiny liberalisations of the rules for Saudi women: he permitted her to smoke in front of his brothers and - a genuinely shocking coup - she got away with crossing the street unaccompanied to visit her sister-in-law.

But as the years went by, she began to fear more and more for her daughters' futures. ''I realised no matter how westernised my husband seemed, he wanted his daughters to behave like true Saudis.'' This meant a lifetime of meek deference to men, whether fathers, uncles, or brothers. ''I wanted my daughters to be free to be what they wanted to be.''

And it meant learning to hate the 'infidel'. Carmen feels that al Qaida's anti-western violence grows naturally - if not inevitably - out of Wahhabism, and notes that his family have stopped short of condemning Osama. ''For me, it's very difficult to believe they have cut all ties with Osama.''

After nine years, when Yeslam took the family to Switzerland on business, she put her foot down and enrolled her daughters in local schools. She also began a battle to divorce her husband which is still grinding on a decade later.

''I realised I wanted them to be free to be what they wanted to be: this is what this book is about.''

l The Veiled Kingdom by Carmen Bin Ladin (Virago, £10.99)