A decline in the number of people worldwide who speak French could cost France 120,000 jobs by 2020 and half a million by 2050 due to missed economic opportunities, a report commissioned by President Francois Hollande said on Tuesday.

"Unless there is a major effort, we could witness a retreat (for French speaking)," the report's author, veteran economist Jacques Attali, said in a foreword. "This decline could lead to a loss of market share for French companies, a collapse in the use of continental law to the benefit of the Anglo-Saxon business law, and a decline in attractiveness for universities, culture and products from France and in French."

Once the international language of royal courts and diplomacy, French has lost ground to English in recent decades, but the report said the right policies in education and industry could increase the number of French speakers from an estimated 230 million today to as many as 770 million by 2050.