Presidents of the French Republic do not start speeches by saying: “To everyone who's important here, bonjour.” They also conjugate their verbs and use pronouns correctly — or at least they did before President Sarkozy.

As Paris marks the annual Week of the French Language, the straight-talking President has upset teachers and purists with his fondness for sounding like a matey, ordinary bloke.

Mr Sarkozy's habit of playing fast and loose with the French language helped him win the election in 2007, but it is now feeding his image as a Philistine. The trouble began early last year when he told a heckler to “p*** off, poor sod” and it has not been eased by implausible attempts by Carla Bruni to portray her husband as a closet lover of belles lettres.

“Molière must be turning in his grave,” said le Parisien newspaper, reporting on the latest Sarkozysmes, as his syntactical abuses are called.

Fanny Capel, the head of a campaign group called Sauvez les Lettres (Save Letters), told The Times: “We have un beauf at the head of the state.” Un beauf, or brother-in-law, is shorthand for uneducated and ignorant.

Mr Sarkozy jangles nerves with colloquial tics such as dropping the “ne” between pronoun and verb in negative sentences. “J'écoute mais je tiens pas compte,” he said the other day. (I listen but I don't take notice). He often uses the slangy “ch'ais pas” for “je ne sais pas” and “ch'uis” instead of “je suis”.

Like Tony Blair with his pseudo estuary-speak, Mr Sarkozy is a lawyer with a posh education who uses low-class tones as a way of endearing himself. The style grates because of France's attachment to language as a unifying force. Most previous leaders have cultivated a literary side, including military ones such as Charles de Gaulle and Napoleon Bonaparte.

The President stands accused of setting a bad example when he is trying to stem a decline in literacy. Jean-Marie Rouart, a writer and member of the Académie Française, accused Mr Sarkozy of pandering to youth “by apeing their vulgarity”.

Jean Véronis, who wrote a study called The Words of Nicolas Sarkozy, said that the President's speech was natural to him. “He is not very cultivated and does not read much. Usually politicians correct themselves when they arrive at a certain level but Sarkozy does not give a hoot. It's his nouveau riche attitude,” he said.

Mr Sarkozy's deliberate philistinism has been turned against him by opponents in the educational and literary world. They are buying in high numbers a 17th-century novel called The Princess of Cleves because it is the President's bête noire.

He joked recently that only a “sadist or an idiot” could have inserted questions on the book into an entrance examination for civil servants. The book has now sold out. Visitors at the Paris book fair last week were wearing badges saying, “I am reading The Princess of Cleves”.

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