By Caroline Wyatt
BBC News, Paris
A French court has fined the company of the man known as the King of Beaujolais, Georges Duboeuf, for mixing premium wine with cheaper grades.
Georges Duboeuf created the popular Beaujolais Nouveau rush
A court in Villefranche-sur-Saone fined the firm 30,000 euros (£21,000) for "fraud and attempted fraud concerning the origin and quality of wine".
Georges Duboeuf said the blend was made in error and that it was never sold to any customers.
His company is considering whether to appeal or not.
The court's verdict is being mulled over with sadness at cafes and restaurants across France.
Mr Duboeuf is one of the best-known wine-makers in the business, responsible for 20% of all Beaujolais production.
He began some 50 years ago - cycling across France selling his wines. His marketing ideas helped create the annual consumer rush for Beaujolais Nouveau.
These days, the company sells 30 million bottles a year, most of it abroad.
The fraud was discovered during a routine check-up by French wine inspectors.
They discovered that after a patchy harvest in 2004, wine from Gamay grapes from superior Beaujolais areas had been blended and then added to the equivalent of 300,000 bottles of Beaujolais.
Such blending is forbidden under the "appellation controlée'' system, even though the aim was to produce a better overall wine.
Inspectors said they had been shocked by what they found.
The production manager involved received a three-month suspended sentence and a fine, after admitting what he called a few slips in the mixing.
Georges Duboeuf himself had pleaded innocent, pointing out that none of the wine had gone on sale.
The ruling comes as a fresh blow to the French wine industry, which is already in crisis over dwindling wine consumption at home and a slump in sales abroad - thanks to fierce competition from New World wines.
French wine-makers, already wary of mixing their drinks, wonder if the situation can get any worse.