In both stories a girl has a traumatic coming of age in northern Italy, rebels, escapes on a bicycle, runs into a man with a drooping moustache, and has a baby.

What happens next is up to the courts, for the similarities between the stories have lobbed a grenade into Italy's usually placid publishing world.

Ippolita Avalli, an acclaimed novelist, is suing her bestselling former friend Susanna Tamaro for plagiarism.

Accusations of betrayal and deceit, themes common to their fiction, are being flung in an increasingly dirty fight.

Ms Avalli is seeking £1.7m damages and wants Ms Tamaro's book, Answer Me, removed from bookshops. Ms Tamaro has responded with a £1m counter-claim.

Ms Avalli's autobiographical 1997 novel The Goddess of Kisses was hailed for its bleak depiction of growing up. Narrated in the first-person in curt prose, it was shortlisted for the Strega prize.

She claims that its plot, structure and vocabulary were ripped off in the title story of Answer Me, a short-story collection which has sold 200,000 copies since its publication earlier this year, making Ms Tamaro one of Italy's most successful authors.

"It was clearly and blatantly plagiarised," Ms Avelli's lawyer Nicola Rocchett, told Panorama magazine.

His court case lists 35 points of similarity. "The plot, characters, style, atmosphere, natural and socio-cultural setting, as well as the premises and conclusions, are nearly identical," he said

In The Goddess of Kisses, published by Baldini & Castoldi, the narrator Giovanna throws a tantrum during mass, condemns the Catholic church and calls the congregation "whitewashed tombs".

In Answer Me, published by Rizzoli, the narrator Rosa smashes a statue of Jesus during mass and calls the congregation "whitewashed tombs".

Rosa, like Giovanna, flees her house on a bicycle and crashes into a man whose moustache is "drooping".

Ms Avalli said there was no doubt about her former friend's guilt. "She and her editor are people who know me very well. There's no way they couldn't have realised it."

She was especially affronted that her character's pregnancy - drawn from her own experience - was replicated, an alleged theft of her private life as well as fiction.

Ms Tamaro denies the accusations and has retaliated in a series of newspaper interviews, claiming to be the victim of pure terrorism.

"I must make an embarrassing confession. I've always copied. I've ransacked St Augustine, Montaigne, Pascal. I've always thought this was called culture," she said.

"And as for the moustache, how many ways can it be? Long, short, curly, or maybe drooping, like my father's?"

If the counter-suit succeeds, the damages will join Ms Tamaro's royalties in funding a charitable foundation. A Milan court will hear the case next month.

The feud is made all the more bitter by the fact that they were introduced by Ms Tamaro's companion, Roberta Mazzoni, an editor at Baldini & Castoldi, who helped to get The Goddess of Kisses published.

Ms Tamaro denied being influenced by her partner when it came to writing her own book. "Absolutely not. I don't have that kind of relationship with Roberta."