On Monday, the leading French farmers' union FNSEA published a map of 18 processing plants, warehouses and supermarkets where protesters were to rally in the evening to protest the low milk price paid by the country's largest dairy processor Lactalis.

As the evening wore on, social media postings revealed the range of actions taken by farmers. In Northern France, they blew a bed of straw into the yard of a Lactalis processing plant in Cuincy.

In the same region, a group of farmers stripped in front of another plant, claiming that Lactalis prices left them "naked", French slang for impoverished.

In the east, they pasted labels with the slogan "This brand is ruining farmers" on products manufactured by the company on supermarket shelves.

The protest has escalated from the blockade of Lactalis's plant and corporate headquarters in Laval, western France last week. Marathon talks late on Friday night ended with a proposal by Lactalis to increase its milk price by 1.5c/l to 28c/l, which farmers' unions rejected.

In a statement at the weekend, farmers union said farmers were "hurt by the Lactalis group's inability to move on from the medieval relationship between a lord and his serfs".

Minister "never met" the country's largest dairy processor

Agriculture Minister Stéphane Le Foll called for further negotiations, saying: "The price paid to farmers by Lactalis, a global leader, cannot remain the lowest on the market. A step forward is indispensable." He also confessed to reporters that he had "never met" Emmanuel Besnier, the head and owner of Lactalis. The privately held company, although the largest milk processor in the country and one of the largest in the world, is notoriously secretive.

On Monday evening, Lactalis was reported to have agreed to a fresh round of talks with farming organisations on Tuesday.

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