When the first nude walkers came over the border the tranquil, neutrality-loving Swiss tried to pretend it wasn’t happening. It was only when it became clear that the invaders had a plan of conquest — even if they had no clothes — that the Alpenhorns sounded the alarm.

Now the Swiss authorities are trying to fend off hordes of German ramblers dressed in nothing more than a rucksack and walking boots. The influx appears to have been started after a German mountaineering website declared the Swiss wilderness a “paradise for naked ramblers”.

“We have been receiving many complaints,” Markus Dörig, a spokesman for the government of the Appenzell Innerrhoden canton, told The Times. “The local people are upset and we in the government share their concern. How would one feel if one was to go walking in nature and suddenly came across a group of naked people?”

But the authorities soon found that they were powerless. When police in the eastern Appenzeller region, which appears to be worst hit by the new craze, arrested a group of German nudists they had to apologise and let them go as there was no law against rambling in one’s birthday suit.

Mr Dörig insisted that the “public nuisance” was a foreign import. “They are definitely not people from the area, and I think many of them come from Germany,” he said.

Swiss legislators have spent the winter trying to find a solution and now they are ready to act. A law stipulating that naked walking is a crime is expected to be enacted this spring. A fine will leave nude ramblers £120 out of pocket — providing they have any — or facing further legal action if they are unable to pay on the spot.

The Bill will be approved by the local parliament on February 9 and should come into force on April 26, when the canton’s citizens gather at the Appenzell town square for an annual vote on legal amendments. The area is well known for its natural beauty but not its liberalism: the canton gave women the right to vote only in 1990 under pressure from the Federal High Court and international human rights groups.

Germany, where freikörperkultur — free body culture — is a respectable pastime, is aghast. The tabloid Bild Zeitung wrote a sniffy editorial about Swiss intolerance and listed nudist alternatives around the world, hinting at a boycott of Switzerland as a tourist destination. One German region has already hit back: local authorities in the Harz mountains in central Germany have announced that an “official naked walking route” is open to everyone wanting to enjoy the outdoors in its — and their — natural state.

Mr Dörig is sticking to his guns. “We are a small and orderly community and such things are simply out of place here. Perhaps in vast mountain areas naked people would not be much of a problem but here they simply stick out,” he said.

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