The book says that Bruni-Sarkozy received a police and security services file in March - including phone call listings and text messages - showing that Dati and Sophie Douzal, the President's ex-sister-in-law, conspired by spreading rumours and stories to have her removed and replaced by Cécilia Attias, whom he divorced in October 2007. Sarkozy married Carla Bruni in February 2008.
The claims are made in Carla and the Ambitious by journalists Michael Darmon and Yves Derai, the day after another, unauthorised, biography hit bookshops in France.
Dati, a former star of Sarkozy's cabinet who fell out of favour with the president, was prepared to "stop at nothing to return to such dizzy heights," the authors wrote.
As a result, she and her fellow plotter "hatched a plan more fitting of the tradition of salon scheming than of a modern political fight. Rachida Dati and Miss Douzal believed Carla Bruni was a weak link in the presidency. Their plan was to bring back Cecilia to the Elysée."
The book says that Dati and Douzal planned to spread rumours about Bruni-Sarkozy's infidelity and stories that Ms Attias was "bored" living in New York and "dreamed" of returning to politics.
After perusing the police report, a furious Bruni-Sarkozy phoned Cécilia in New York, where she lives with her new husband Richard Attias and Sarkozy's youngest son Louis, to warn her against taking part in the plot.
"I have to inform you that two people with whom you are in contact are behaving in an unacceptable way with regard to us. These people are your ex-sister-in-law Sophie and Rachida Dati. This is not my suspicions or idle gossip. I have a police file that you can see. I know you have nothing to do with these women but I urge you to keep your distance from them," the Telegraph quoted her as telling Attias.
Dati and the Elysée declined to comment. (ANI)