Production at the world's biggest Nutella factory has come to a near-standstill in a showdown over salary negotiations.
Tensions have been mounting at the site in Villers-Ecalles in Normandy, where activists from the Workers' Force union have been barring trucks from entering or leaving the factory for a week.
The factory makes a quarter of the world's Nutella stock - that is 600,000 jars of the chocolate and hazelnut spread every day.
After six days of failed efforts to end the stand-off, Nutella owner Ferrero has started threatening fines for workers involved in the blockade, according to a company statement.
Even this has not deterred unions. Workers' Force says 160 of the factory's 350 workers are taking part in a walkout to demand 4.5% salary increases, one-time 900-euro bonuses and better working conditions.
Fabrice Canchel of the Force Ouvrière (FO) union said 160 employees had been on strike since 27 May. “No lorry has gone in or out of the site since then,” he said on Monday.
Meanwhile union activist Fabien Lacabanne said: "It's war, anger is mounting."
He said the company agreed to a 1.7% raise for the lowest paid workers, and one-time bonuses between zero and 400 euro, which unions say is not enough given rising living costs. Unions also complain of deteriorating factory conditions and increasing pressure to be more productive.
Italian-owned Ferrero said it is trying to protect workers who are not on strike, and wants to resume dialogue - but not until the workers stop blocking the factory.
The next negotiation meeting is scheduled for June 13.
French workers frequently go on strike during salary negotiations and occasionally resort to more dramatic methods. The last strike to hit the Villers-Ecalles factory was in 2011.
The action comes amid anger among many low-income French workers at pro-business policies by President Emmanuel Macron seen as favouring the rich - and that prompted the yellow vest protest movement.
As a result, production of Kinder Bueno has been halted for almost a week, while only one of the four Nutella production lines is working, at 20% capacity. “The raw materials are starting to run short,” Canchel said.
