Valery Giscard d'Estaing, former President of France, former finance minister, member of parliament and president of the regional council of his native Auvergne, doesn't see what all the fuss is about. But his nonchalance veils a simmering irritation towards the ecologists who want to scupper his volcanic theme park.

In Mr Giscard's mind, the European volcanic centre he has worked for since 1992 means progress, tourism and economic development for his backward region. A contest among secondary school pupils chose the name "Vulcania" for the Ffr 420 million (£46.66 million) project - the prize was a free trip to Vesuvius - and a few days ago the bulldozers began digging the underground museum.

His inspiration, Mr Giscard told The Irish Times in a telephone interview, was the underground museum dedicated to the conquest of the far west in St Louis, Missouri. "Our region looks a little like Ireland or Scotland, with superb chateaux and Roman churches," Mr Giscard said. "But in Auvergne we have nothing like the Mont Saint Michel to attract tourists. The one thing we do have are 8,000 year-old volcanoes." As both advocates and opponents of the plan are quick to tell you, the 80 extinct volcanoes of the Chaine des Puys mountain range are unique in Europe. Vulcania is expected to draw more than half a million tourists each year.

A 20-metre-high artificial volcano will mark the entry to the underground museum, its interior lined with shining copper. "When the sun shines on it, it will give the illusion of eruption," Mr Giscard enthuses. The theme park, 10 km west of Clermont-Ferrand, will be built on three levels, to a depth of 35 metres below ground. The rooms will be dug out of basalt rock, and there will be bubbling mud, geysers, smoke and hot lava in the connecting tunnels.

No gadget will be too expensive for Vulcania. Cameras as far away as Iceland and south-east Asia will transmit real-time images of volcanic eruptions. Tropical gardens will show visitors the lush vegetation that grows in volcanic soil. "The visit will end with a huge volcanic explosion on a giant screen," Mr Giscard adds. "It will be the biggest size screen that exists, a semi-circular one." He hopes to inaugurate the theme park in July 2000, and wants it to be "the biggest millennium event in France, possibly in Europe".

If Marcel Breugnot and the Liaison Committee for the Protection of the Volcanoes of Auvergne have their way, however, Vulcania will remain dormant. The battle over Vulcania has become personal. "Giscard wants to leave a monument to himself after his death," Mr Breugnot, a 70-year-old retired tax collector, accuses.

Opponents have collected 18,000 protest signatures. They are not against the idea of a museum further away from the Chaine des Puys, outside the natural park, but claim the project is too expensive, that it will urbanise the area and endanger an underground river that provides water for 100 towns.

Mr Giscard - who at 71 is one year older than Mr Breugnot - dismisses the ecologists as an insignificant bunch of complainers. "It's a small, very negative group. They're old people who have nothing to do," he says. He even likes "Giscardoscope", the name the environmentalists gave his project in derision. "It was clumsy of them," he says. "It evokes a success in people's minds - the `Futuroscope' (scientific theme park) in Poitiers." The conflict has, on occasion, turned ugly. After the regional council received an anonymous death threat on the fax machine, the police searched the homes of environmentalists. The Human Rights League denounced the "judicial harassment" of the project's opponents, saying there was "total disproportion" between the offence and the heavy-handed tactics of investigators.

The recent appointment of a leader of the Green party, Dominique Voynet, as minister of the environment encouraged the opponents. Mr Breugnot believes she will intervene to stop Vulcania. Mr Giscard is equally confident. "That's impossible," he says testily. "We live in a country of laws. We own the land and we have the building permit. It can't be reversed now."