The threat, which emanates from the Loire valley but covers a lot of France's main pig producing area, is as vague as it is potentially disruptive.

The ultimatum comes as supermarkets and suppliers face a 28 February deadline to conclude legally binding supply contracts for 2011.

There are growing numbers of pig farmers in the region who face bankruptcy as their holdings have lost up to EUR 30 per pig over the past three years, while retail prices (for loin products) have remained stable.

Last year a delegation of pig farmers from the Loire regional farmers' union visited Germany on an inconclusive factfinding mission. Among the oversights noted at the time by the Marché du Porc Breton (MPB) was the direct comparison between a (lower) French price based on farmgate collection and a (higher) German price based on abattoir arrival (delivered).

Since then, cereal prices have risen steadily and the German dioxin crisis has hit the press, to the growing dismay of producers in France's largest pig region.