The Constitutional Council of France has issued a bill allowing schools to teach most of the day in minority languages, such as Basque, Breton and Corsican.

Government-funded schools can provide two-lingual education, but the French parliament adopted in April a draft law which allowed primary schools to teach, while teaching French, the majority of schools in a regional language.

The education ministry requested the proposal, however, arguing that so-called “immersive education” could mean that the required level of French language skills would not be reached for children.

The “Molac bill”, named after MP Paul Molac from Brittany who championed the legislation, was aimed at boosting regional languages, which also include Catalan and Creole.

“The Council’s censure is incomprehensible for the regions. We must stop being afraid of regional languages, we should protect, cherish, and save them,” Molac said on his Twitter feed.

The Council, France’s highest constitutional authority which must approve all new legislation, ruled that the bill was out of line with article two of the French constitution, which stipulates that the language of the French republic is French.

For the same reason the council also struck down the bill’s proposal to allow non-French so-called diacritical marks such as the tilde, in official documents.

The French language has several such diacritic marks, such as the acute, grave and circumflex accents and the double-dot trema on several vowels, as well as the cedilla under the letter c, notably in the word français.