The centuries-old language watchdog Academie Francaise has warned that growing use of English by public and private bodies risks poor communication and could even undermine social cohesion.

A report by six members of the body, adopted in early February and published online this week, warns that "today's communication is characterised by a degradation that must not be seen as inevitable".

Over 30 pages, it picks through dozens of messages from public bodies such as ministries or local authorities, as well as private firms, highlighting examples of bilingual wordplay.

The flagged terms include train operator SNCF's low-cost "Ouigo" (pronounced "we go") services, or simple imports from English like "big data" or "drive-in".

"Many anglicisms are used in place of existing French words or expressions, inevitably leading to the gradual erasure of the French equivalents," said the body, which was founded in 1635 under King Louis XIII to guard "pure" French.

"Aside from fashion and sport, the internet and digital field is unsurprisingly the most strongly and visibly 'anglicised'," the Academy said, dubbing tech terms "Californisms".

In one example, it notes that there are at least five possible French translations for the social-networking term "follower", a word commonly peppered into everyday French speech.

The Academie Francaise was founded in 1635 under King Louis XIII to guard 'pure' French
The Academie Francaise was founded in 1635 under King Louis XIII to guard 'pure' French AFP / Eric Feferberg

The Covid-19 pandemic has also resulted in a number of hasty bolt-ons from English like "cluster" and "testing".

English words themselves are "often distorted" to fit French pronunciation or syntax, the Academie notes, resulting in "the creation of hybrid forms that are neither English nor French".

Sometimes this can make even fluent speakers stumble -- as with carmaker Peugeot's slogan "Unboring the Future" or the concept of a "drive pietons" (a "pedestrian drive-through", or pick-up point for products ordered online).

Overuse of English "has the contradictory consequence of risking both an impoverishment of French vocabulary and growing discrimination among sections of the public," the Academie said.

"By widely using an English vocabulary not understood by much of the public, online services contribute to stoking the defiance that has visibly developed in recent years towards all kinds of authorities."

The Academie Francaise has become more assertive under permanent secretary Helene Carrere d'Encausse about its mission to protect French.

In January, it threatened legal action against the government for including English translations of information fields on national identity cards.