Carla Bruni books reveal there are two sides to every story

A much-awaited "unauthorised" biography of the French first lady, Carla Bruni-Sarkozy, published yesterday, paints a scathing picture of a vain and selfish woman who neglects her official and charitable work.

But the Elysée Palace has not allowed the book's author to have the field to herself. Having failed in a bid to block its publication, Ms Bruni's supporters are reported to have encouraged the writing of a rival biography that is to be published tomorrow – and which is said to paint a far more positive picture of the supermodel and pop singer.

It is not clear that the unauthorised volume will present them with the publicity difficulties that they might have initially feared. Although the book is entitled Carla Bruni, une vie secrète it contains few revelations on the past, or present, life of Ms Bruni, who married the French President in 2008.

Shocks are even less likely to abound in the authorised alternative. Carla and the Ambitious was prepared with the co-operation of the first lady, and the authors, Yves Derai and Michael Darmon, focus their attention on her time as the President's wife.

Besma Lahouri's book, in contrast, traces Ms Bruni's volcanic love affairs with a series of celebrities, including Mick Jagger and Eric Clapton, before she met President Nicolas Sarkozy in 2007. It quotes an unnamed plastic surgeon as claiming that he remodelled Ms Bruni's nose when she was a young woman – something that she has always denied.

It suggests that the French first lady's foundation to combats Aids is an "empty shell" and that Ms Bruni, 42, is so neglectful of her official and charitable work that she is known in the Elysée as the "anti-Diana". Similar allegations have already appeared in the French press.

However, the book suggests that the notion that Ms Bruni-Sarkozy is a "man-killer" who spits out her victims is quite wrong. Rather to the contrary, it says, she likes to preserve good relations with all her old boyfriends, like trophies or flies in a spider's larder.

This habit is said to be one of several sources of friction with President Sarkozy. "He has to deal every day with this troublesome tribe," the book says. "Singers, philosophers, lawyers, bosses, pressmen and politicians, the organigram of her former loves is rather large." During the couple's holiday in Carla's mother's villa in the south of France last year, the house guests included three of her former lovers, the book says.

However, Ms Lahouri adds nothing to the speculation earlier this year – now largely discounted – that both Nicolas Sarkozy and Carla Bruni-Sarkozy were having tit-for-tat affairs. The author says that she interviewed 100 people for the book and had, for legal reasons, to make many cuts and changes.

The author believes that Carla Bruni-Sarkozy's principal ambition is to outshine Michelle Obama, whom she sees as the only person "able to challenge her for the title of the world's sexiest and most glamorous first lady". The book suggests that the frosty relations between the French and US presidencies have largely been caused by tensions between the two women.

In pre-publication interviews, Ms Lahouri suggested that her portrait might shock many French people. "The French don't know their first lady, and her worries seem to them very far removed from their own," Ms Lahouri said.

Who is the real Carla? "I don't think she knows herself," she said. "In the last two years, she has rewritten her life story, changed her image and reneged on her old gut instincts of the left. I only know one thing. The Carla that the French see in public is not the real one."