Bruni reveals use of secret service files to find out truth about marriage rumours

In the book it’s been stated that Bruni obtained lists of telephone calls and text messages made by those she suspected were plotting against her.

Meanwhile, husband and President Nicolas Sarkozy is already fighting claims that his office spied on newspaper Le Monde. The newspaper said intelligence services were used to identify a source.

The book suggests that claims about Bruni’s failing marriage arose from meetings with former Justice Minister Rachida Dati and a woman who was previously Sarkozy’s sister-in-law, with the aim of bringing Sarkozy’s former wife Cecilia back into Elysee Palace in France.

The book says Bruni phoned Cecilia as soon as she became aware of the plot.

The book says Ms Dati, who is now a member of the European parliament, was prepared to "stop at nothing to return to the dizzy heights" of government.

When it was reported in April that Ms Dati was behind the rumours of the president's marital problems, Carla Bruni came to her defence.

"The accusation that Rachida Dati was behind these rumours is a rumour and I don't believe rumours. Rachida Dati absolutely remains our friend," she had said on French radio.

The revelation that the presidential couple used secret services to investigate rumours about their marriage came at a bad time for the Sarkozy, when earlier this month, police searched the main offices of President Sarkozy's political party as part of an inquiry into claims that the L'Oreal heiress had made illegal donations to his presidential campaign.