Plans to build a hydro-electric plant near the Swiss border have soured centuries-old relations between an Italian town and Canton Ticino neighbours worried about the fate of their Isorno river.
The feuding broke out a few weeks ago when a company based in the Piedmont town of Verbania announced it was about to begin work on a 21-million-kilowatt plant on the Italian side of the Onsernone river, in the picturesque Bagni di Craveggia area.
Canton Ticino residents claim the plant will drain water from the Isorno river and will threaten water supply throughout the Canton.
"This is a truly delicate issue for us because the Bagni and Isornia streams flow into the Isorno River in the Onsernone Valley. These are frontier waters which fall under international jurisdiction," said Swiss MP Francesco Cavalli.
The townspeople of Onsernone and Spluga have held a protest march and Cavalli has raised the issue in the Swiss parliament, saying the plant would deal "a death blow to the valley".
So far, their Italian neighbours have shown little sympathy.
But Italian environmentalists have rushed to the Swiss villagers' defence, asking a renowned Milanese university professor to draw up a report on the possible damage the plant would cause to an area which thrives on tourism.
The Italian Association of Mountain Climbers CAI has also expressed concern for what it says would be a "mushrooming of buildings and constructions" which would spoil the scenery of the valleys.
The Italian chapter of the World Wide Fund for Nature and the Greens have warned that the historic Bagni di Craveggia thermal area is in peril.
The properties of the spring and hot thermal waters in Bagni di Craveggia have been a major attraction since the fifteenth century, drawing tourists from both sides of the border.
But the Italian road leading to the Craveggia spring was destroyed by a landslide in 1951 and since then the area can only be reached from the Swiss side, via a road from the town of Spluga.
Last month, in a move worthy of Western movie feuds pitting ranchers battling over cattle grazing territory, Spuga decided to block Italy's access to the road.
Italians interested in taking a dip in the thermal baths are now forced to make a six-hour-long trek up the mountains to reach Bagni.
The move prompted Italian MP Marco Zacchera, of the right-wing National Alliance Party, to question Foreign Minister Massimo D'Alema on how to respond to what he termed "the military occupation of the border".
