Vintners have said the bridge will destroy the unique wine-growing environment of the south-west valley famed for its world-class Rieslings, as well as become an eyesore on an unspoilt beauty spot.

“We fear for the valley. It is going to be dead in 10 years’ time,” Knut Aufermann, a member of Pro-Mosel, an anti-bridge movement, said.

Opponents of the 10-column, mile-long bridge claim its presence will affect the soil quality and irrigation of the valley’s steep, slate sides, and cast an unwelcome shadow over the vines. 

Hugh Johnson, the British wine expert behind the annual Pocket Wine Books, added his voice to the protests.

“This mad, destructive, unnecessary road is on course to pollute the most famous, most beautiful and historic stretch of one of Europe’s loveliest rivers, forever,” he said.

• Germany to build motorway through Riesling vineyards28 Jun 2010

“It is shocking to watch how German politicians are selling out and destroying one of their finest cultural assets.”

But the Rhineland-Palatinate state government, which approved the plan, said the bridge will help bring in more tourists to the region, and Werner Schmitz, the mayor of the Urzig, which will lie near the bridge, said that 90 per cent of the town’s population approves of its construction.

Its supporters also claim that the bridge, estimated to cost £250 million, will cut travel time between the Dutch and Belgian coasts and the heart of German commerce in Frankfurt.

Bridge opponents were especially angered by an apparent change of heart by the Green party over the construction project. The Greens had long fought against plans to span the valley but in a state government meeting this week gave the green light to the project.

Sarah Washington, spokesman for Pro-Mosel, said she thought the Greens had backed the plan to maintain a new coalition with the Social Democrats formed after state elections in March.

The go-ahead for the bridge ends a saga dating back to the Cold War when a plan for a crossing at the Mosel Valley was first mooted by US forces, frustrated by the time it took to travel between bases either side of the valley.

Construction had started two years ago but was halted by environmental concerns. www.wine-business-international.com