She is the daughter of a famous German professor and, at 17, already has a best-selling debut novel about sex, drugs and teenage self-discovery in its third edition - and nominated for a major literary prize.

Some have labelled Helene Hegemann insufferably precocious. But if her ego had swollen at the praise, it has now been dramatically punctured by a torrent of criticism since Axolotl Roadkill appeared in bookshops last month. Hegemann is now at the centre of a literary row about plagiarism.

Hegemann, whose father is German literary director and theatre professor Carl Hegemann, has already written a play and film script.

But her novel about a 16-year-old girl who, after the death of her mother, plumbs the depths of wild sex and heavy drug-taking on Berlin's techno music scene was her first runaway success.

The book was nominated for the Leipzig Book Fair's prestigious fiction prize and last week reached second place on the German best-seller lists. Publisher Ullstein has printed more than 100,000 copies.

Yet Hegemann now faces allegations that she stole chunks of material for her book.

A key inspiration for her book was a far less well-known novel called Strobo, by a 28-year-old Bavarian blogger who writes under the name of Airen.

Strobo's author moved to Berlin a few years ago. He uses a pseudonym and claims he would alarm his employers if he revealed his identity. His book, a compilation of his blogs, is his account of hedonistic experiences in Berlin's underground scene.

A blogger pointed out that passages of Hegemann's book bore similarity to Strobo. One page had simply been lifted. "There was really no need for her to copy me," Airen said. "But she borrowed entire passages of my dialogue."

Hegemann's publishers have gone on the offensive, turning what appears to be a case of stealing into a debate about the meaning of plagiarism in the online era. They argue that Axolotl Roadkill is an example of "intertextual mixing".

Hegemann's defence is simply, "I cannot understand what all the fuss is about."

While she acknowledges that she used numerous sources for her book, she also claims that she is a member of a generation of writers adapting information online for their own creative purposes.

"There is no such thing as originality anyway, there is just authenticity," she told Der Spiegel.

She appears to have won over Volker Weidemann, a member of the Leipzig Book Fair Jury and a book critic for the Frankfurter Allgemeine newspaper.

"Obviously it's not completely clean, but for me it does not change my appraisal of the text. I believe it's part of the concept of the book," he insisted.

In Axolotl Roadkill one of Hegemann's characters spells out the author's philosophy:

"I help myself wherever I find inspiration and ideas: films, music books, paintings, poetry about sausages, photos, conversations, dreams... light and shadow, precisely because my work and my theft become authentic the moment something touches my soul. Who cares where I get things from? All that matters is what I do with them."

"So it's not by you then?" another character asks. "No, it's by some blogger," is the response.