PARIS: The French President, Francois Hollande, has provoked outrage by writing to a court that is hearing a defamation case brought by his partner.
Valerie Trierweiler, 47, is suing two journalists over claims that she was sleeping with Mr Hollande while she was also the mistress of Patrick Devedjian, a married right-wing former minister.
Mr Hollande was still with the mother of his four children while conducting a four-year affair with Miss Trierweiler, their book alleges.
Miss Trierweiler is seeking €80,000 ($A98,000) in damages and €5000 in legal fees from the authors Christophe Jakubyszyn and Alix Bouilhaguet for "defamation and invasion of privacy".
In a short handwritten note to the court, Mr Hollande complains that parts of La Frondeuse (The Troublemaker) are "pure fabrication". But the two pages with which he takes issue have nothing to do with Ms Trierweiler's romantic past and relate to domestic French politics in the 1990s.
The letter, sent on Monday, was denounced by Eric Ciotti, a centre-right MP, as a "staggering and shocking" attempt to put pressure on the judiciary from a man who has pledged to steer clear of the courts while in office, unlike his predecessor Nicolas Sarkozy.
Olivier Pardo, a defence lawyer, said: "The separation of powers has been violated. The President is the guarantor of the independence of the judiciary. This is absolutely incredible."
Adding to the controversy, Manuel Valls, France's Interior Minister and Ms Trierweiler's friend, also wrote to the court, admitting he was interviewed by the authors for the book, but only on the assumption that it would be "favourable" to the first lady.
Mr Valls said quotes attributed to him were "often partial and out of context".
The latest row comes at a bad time for the President as he struggles with low approval ratings over his handling of the economic crisis.
In his letter, Mr Hollande denies a claim that he had sought an alliance with the centre right in the 1990s.
The allegation is politically embarrassing for a left-winger - even more so on a personal level, as his main contact on the right was allegedly Mr Devedjian, his rival for Ms Trierweiler's affections.
Jean-Francois Cope, the interim leader of the opposition UMP party, said: "I am very, very surprised to see a Socialist president, who gave us lots of moral lessons in the past, involving himself in a legal procedure.
"I wonder what reasons could have led Mr Hollande to give Mr Sarkozy so many moral lessons and not to apply them to himself."
Frederique Giffard, Ms Trierweiler's lawyer, denied Mr Hollande was seeking to apply any political "pressure" on the court, and a friend said it was a "personal testimony".
Ms Trierweiler is also suing celebrity magazine Point de Vue for €70,000 after it ran an interview with the authors who reiterated the claims that she had had an affair with Mr Devedjian.
Miss Trierweiler caused an outcry in June by tweeting support for a Socialist politician standing against Segolene Royal, the mother of Mr Hollande's children. She has since been criticised for keeping her press card while launching a stream of actions against journalists for invasion of privacy.
Last week Bernard Debre, a former conservative minister, said she was "nothing more than the President's mistress" and should "stop meddling" in the country's affairs. Yesterday she was accused of doing just that after meeting opponents of a controversial new airport, despite the fact it is backed by Jean-Marc Ayrault, Mr Hollande's Prime Minister.
The judge in the defamation case will rule on the defendants' request for an annulment on January 28. It the application is rejected, the case will go to trial.