Burgundy, Chianti, Rioja and other quality European wines will be under threat if radical EU reforms are approved next month, top winemakers say.
Producers from France, Italy, Spain and Portugal warn that the plan EU agriculture ministers are due to vote on in mid-December will undermine their viability and be challenged in court.
They are incensed by plans to scrap the EU's existing ban on planting new vines after 2013 and what they claim is the use of the geographical indication (GI) system to limit output of protected-label wines.
Land planted with vines in GI regions usually compromises only a small part of the "protected" area.
For example the Rioja region encompasses 350,000 hectares but only 60,000 hectares of vines are planted there. Chianti has 35,000 hectares but only 17,000 hectares covered in vines.
EU ministers want to exploit more than one million hectares of new "quality" potential, which is affected by the planting ban.
The GI producers fear that, after 2013, removing the ban would result in a free-for-all on unused "protected" land. This would likely lead to lower prices due to oversupply and an undermining of quality and the reputation of long-established labels.
"The liberalisation of planting rights can only destabilise the GI sector, which is the main asset of the EU wine sector on an increasingly competitive world market," said Christian Paly, president of the French "appellation controlee" producer body CNAOC.
But Michael Mann, the Commission's agriculture spokesman, said there is no intention is to undermine the quality of current GI regions.
The GI wine producers commissioned a legal analysis of the Commission's reform plan, which they said contained various elements that appeared to be open to legal challenge, both inside and outside the European Union.
"If the Commission sticks with its proposal ... it's clear that there will be tens of thousands of legal cases against it from wine producers," Mr Paly said.
The EU is the world's largest producer, consumer, exporter and importer of wine. In recent years it has lost part of its traditional export markets to cheaper wines from Australia, Chile and also the United States, and seen a surge in imports.