A replacement facility at Soulaines in the Champagne region has also begun contaminating ground water -- though at far lower levels -- 10 years after its construction, Greenpeace said.

The group sent bottles of contaminated La Manche ground water to French senators due to begin on Wednesday debating a law authorising the burial of highly radioactive nuclear waste deep underground, notably in an area bordering the Champagne region.

"The pollution of ground water in La Manche is already very serious," Greenpeace campaigner Frederic Marillier told Reuters by telephone.

"The fear we have is that, with this plan for a new storage site in Champagne, in the future there will be a radioactive pollution in this region which has a very, very special nature."

France sold around 300 million bottles of the famous sparkling wine last year, with around 55 percent of production consumed in France, 45 percent exported.

ANDRA, the French agency responsible for managing nuclear waste, confirmed in a statement placed on its Web site on May 24 that Soulaines had leaked. It said it had ordered repairs and that no harm had been done to the environment.

Marillier said Soulaines water samples showed 17 becquerels of radioactivity per litre last year, a rise from 2004 but still well below the EU alert level of 100 becquerels.

Samples from near the La Manche site, close to the La Hague nuclear reprocessing facility on the Channel, showed tritium pollution was 180 times the EU safety level, Marillier said.

France, the world's second-largest nuclear power producer, has accumulated radioactive waste for 40 years and its storage is a contentious issue.