Environmental and citizens' rights groups in France are appealing a government decision to classify all nuclear-related information in France as defense secrets.
The information ban, which was declared in August, not only covers nuclear defense matters, but also the country's nuclear power plants, which generate more than 75 percent of France's electricity and export power to other European countries.
Violators risk up to five years in prison and nearly $90,000 in fines.
The issue of secrecy has become a critical one for the French government since the September 11, 2001, terrorist strikes in the United States. It was shortly thereafter that France stepped up security around its nuclear reactors, for fear of other attacks.
But critics argue that the new ban violates citizens' rights to know, including information about nuclear waste and plutonium being transported across the roads of France.
The trucks and trains carrying the material have these cargoes encased in heavy protection. Nonetheless, Greenpeace spokesman Michel Luze says an accident could be disastrous if local authorities are unaware that the material involved was nuclear-related.
"For instance, there are hospitals near the roads they use, and they don't know there is such a transport," he said. "What would happen if an accident occurred ... if the hospital doesn't know what to do? If they don't even have an emergency plan to rescue people. The same for firemen."
Over the years, concerns about the hazards of transporting nuclear material have sparked major protests around the world. But there have also been incidents, such as a plutonium theft in Germany, that have fueled government concern.
Many European countries have been phasing out their nuclear reactors since the Chernobyl disaster in Ukraine 17 years ago.
France, however, remains heavily dependent on nuclear energy. And on Wednesday, the French government announced it was considering constructing yet more nuclear reactors.