TAHAR Ben Jelloun is “Morocco’s greatest living author”, according to the blurb on the paperback edition of his latest book, About My Mother, which he began in 2001 and finished in 2007. The accompanying press release also claims that he is “regularly shortlisted for the Nobel Prize in Literature”, although the names of nominees cannot be revealed until 50 years later. But let us pass on that.

In any case, the distinguished novelist, essayist, critic and poet has yet to win. He has, however, been awarded the Prix Goncourt – the first North African to do so – and the International IMPAC Dublin Literary Award. In France, where he and his wife (with whom he has four children) have lived for more than 45 years. He also received the rank of Officier of the Légion d'honneur in 2008.

Many of his North Africa-set international bestsellers, all of which he writes in French despite his mother tongue being Arabic, have been translated into English, including The Happy Marriage, This Blinding Absence Of Light, The Sand Child and Racism Explained To My Daughter. Winner of the 2016 PEN Promotes Award, All About My Mother is a genre-defying, lyrical, moving tribute to Ben Jelloun’s late mother, thrice-married Lalla Fatma, translated by Ros Schwartz and Lulu Norman.

But is it a novel? A memoir? A biography of an ordinary woman? A case study of the living death that is Alzheimer’s disease? Or is it a social history of Moroccan domestic life? It is all of these – as one reviewer has suggested – and much more, a blend of fact and fiction as vivid as one of Lalla Fatma’s gorgeous headscarves in colours that she believes should make the heart beat faster.

So, a meeting with the great Ben Jelloun is keenly anticipated. But, reporter, be careful what you wish for. He arrives with interpreter and publicist at the London hotel near the BBC, after being interviewed for the Arabic service. Looking irritated before we are even introduced, he tosses his fedora and a long blue scarf, which I have offered to take from him, onto the sofa alongside me and proceeds not to engage in any eye contact, although he does so eventually, of which more later.

There is nothing more disconcerting than an interviewee who refuses to look you in the eye and who is more interested in the London skyline from 15 floors up than in having anything approaching a conversation about his work. Indeed, the strength of the double glazing is tested as he bangs his fist on it at one point – not out of anger but more idle curiosity I suppose, or perhaps he’s trying to escape.

We discuss the unclassifiable nature of the book, which he embarked on when his mother first fell ill, becoming “a frail little thing with a faltering memory”, summoning long-dead members of her family – “We’re living with ghosts here,” he writes. She talks to them as they file past her bedside, sometimes they linger. He doesn’t interrupt them. He doesn’t like to upset her.

Her paid companion tells 69-year-old Ben Jelloun that his mother thinks that she is in Fez in the year of his birth. She constantly revisits his childhood: “Her memory’s been toppled, lies scattered over the damp floor. Time and reality are out of kilter.”

The book was originally a diary of Lalla Fatma’s illness. “Then in the end I just changed it all and it became a novel. Yes, it is hard to categorise and it is all [the genres] you have described but it’s a book about mothers and people’s relationships with their mothers, which is why it is appealing to readers in more than 20 countries and has been translated into as many languages,” says Ben Jelloun, speaking in rapid French through an interpreter.

The book changed, he explains, because as she became more and more delirious, his mother told him stories about her life that he was not aware of. “And so I invented her childhood; I invented her life. It was almost like making a puzzle. I put all those pieces together and some pieces were real and from her; some were not. It’s a mixture.

“Many things I discovered surprised me, because in a Moroccan family the mother is always very discreet. My mother, who was illiterate but intelligent, would never have talked about her private life or her sexuality with her sons. Suddenly, she gave these little hints. She had had another child who must have died and I wasn’t aware of that. The book mixes souvenirs of my childhood and her memories but it’s not a personal story. In a way, I appropriated her life, but I’ll never know whether it is precise or not because she is no longer here to verify it. I told her I was writing the book, which she would not have liked at all, with me revealing her incontinence, for instance. In a way, I suppose I am stealing her life, her small, beautiful life.”

It is an accusation that has been levelled at Ben Jelloun in the past. His multiple award-winning 2001 novel, This Blinding Absence Of Light, is based on the true story of a former inmate of one of Hassan II’s notorious desert prison camps – an officer accused of collusion in a failed coup and interned for 20 years in an underground cell. Ben Jelloun drew on a three-hour interview with a survivor (whose brother had asked Ben Jelloun to tell the story), who later accused him of having stolen his story. But a financial agreement had been signed and a draft approved by the survivor, to whom the book was also dedicated. It was nonetheless a bruising experience.

So much so that Ben Jelloun went on to write for the first time about his own spell in detention in his Tangier-set novel, The Last Friend (2004). In 1966, while reading philosophy at Rabat University, he was arrested for taking part in a student demonstration in Casablanca. He was interned in a prison camp for 18 months. Books were banned but his brother smuggled in the thickest paperback he could find – James Joyce’s Ulysses. Fascinated by this “writer’s liberty”, Ben Jelloun began writing poetry in French.

On his release from the camp, he taught philosophy, but left for France in 1971, where he did a doctorate in social psychiatry and published his first novel, Harrouda (1972). By this time he had discovered many more inspirational writers, such as Cervantes, Borges and Jean Genet, whom he befriended and liked very much.

We return, though, to his mother – “a woman full of goodness, incapable of speaking ill of people, a believer with great faith in God” – and to Zilli, his friend Roland’s flamboyant mother, about whom he also writes, comparing and contrasting the two women’s lives. “Zilli did everything!” he exclaims, looking positively animated and finally making eye contact. “She went on cruises, she played the piano and she played tennis. She went riding. And she had lots of lovers! If you compare the two lives, my mother’s life was empty. But my mother compensated by being very generous, a committed mother, a woman who never got cross. In her final years, I spent days and days with her. The longer I was with her the more I got used to her leaving me.”

I ask Ben Jelloun why he writes in French rather than Arabic. “I prefer to test myself in a foreign language,” he replies. “I love French. Had I written my books in Arabic, they would be bad books. I just don’t master the language.”

Currently he is not working on another novel, but focusing on writing about terrorism in France and has recently been talking to schoolchildren about it.

“I am very worried about the situation,” he says brusquely. “It is a war like no other war. We don’t know who the enemy is, but he is not scared of losing his life while we are scared of losing our lives.”

I open my mouth to ask him about the political situation in North Africa and the refugee crisis – we meet shortly before last weekend’s [October 29] mass protests in Morocco – but suddenly he stands up, announcing that he is tired. We have been talking for barely 25 minutes. The fedora and scarf are retrieved and he leaves after signing his book. Finally, he asks my name.

About My Mother, by Tahar Ben Jelloun (Telegram, £8.99).