The continuing story of violence in the French wine industry took a sinister turn this weekend, when an ultimatum from a radical group of winemakers to French President Nicolas Sarkozy ran out.

The French President received demands from a militant organisation called CRAV (Comité Régional d'Action Viticole or regional winegrowers' action committee) via a videotape a month ago. In the tape, the group threatened violent action if measures were not put in place to alleviate the economic plight of wine growers from the Languedoc-Roussillon area. The deadline imposed on Sarkosy ran out on Sunday (17 June).

The video, shot at night, features seven winemakers disguised by black balaclavas who threatened that "blood will flow" if Sarkozy doesn't make plans to raise the price of wine.

Supermarkets selling cheap foreign wine have already been targeted in recent months, with small explosive devices, whilst others have been vandalised with graffiti. However, it is now feared that with the passing of the latest ultimatum, the violence could escalate.

"If Sarkozy does not support the interests of the wine industry, he will be entirely responsible for what happens," a winemaker in the video said. "We are at the point of no return."

And speaking in the UK newspaper The Observer, one French policemen explained that they were taking the threat seriously. "They are influenced by Corsican and Basque separatists, both of whom have ruined many lives and caused major economic disruption. They sound amusing and colourful in a typically local sort of way but they are not. They have killed people in the past," he said.