A once tiny village nestled underneath Mont Blanc, it was developed by the Rothschild family after the First World War into France’s showpiece mountain resort.

It was here, in 1927, that the first ski school opened in the Alps. Since then, thousands of moniteurs – instructors – have emerged, resplendent in red kit, elegantly whooshing down snow-covered screes – and leaving more than a hint of aftershave and cognac in the crisp mountain air. It is also where a group of instructors has decided to make its last stand: on Megève’s slopes, piste wars have once again broken out. This time the French mean business.

Over the weekend, in unprecedented scenes, seven British ski instructors were arrested in what they described as a “carefully orchestrated operation”. Simon Butler, 51, who has worked in the resort for nearly 30 years, was hauled by armed police off a ski lift in front of half-term crowds to spend a night in the cells. Six of his British colleagues were also arrested.

The authorities accuse them of teaching without the proper qualifications – an offence which can carry a prison sentence of up to three months. There has been ongoing harassment of British ski instructors for some years now; however, this is the most extreme response yet. For Butler, his misdemeanour is simple, “My only real crime was being British, not French.”

International tensions on the slopes are largely a result of EU laws that allow citizens to seek work in neighbouring countries. The sheer number of English arriving to do a season in the Alps has created a new bête noire in the region, prompting the Libération headline: “Europe: After the Polish plumber, the English ski instructor”.

The issue at the heart of the latest arrests is the demands of the Ecole, which oversees ski instruction in France. Foreign instructors need to be working through their qualifications with a certified French ski school or – a requirement not standard in the ski world – hold the top-level ISTD qualification from the British Association of Snowsports Instructors (BASI).

Critics feel this gives preferential treatment to French moniteurs. In The Daily Telegraph, Boris Johnson, the Mayor of London, yesterday called the situation “a complete, naked, shameless and unrepentant breach – by the French – of the principles of the European Single Market”. Mr Butler feels similarly, and he is filing a complaint with the European Commission.

It is not just on the ski slopes where British people are running into problems. “France is very bureaucratic, much more so than England, and it can be quite frustrating at times,” says John Kinnear, who runs Stanford Skiing in Megève. He spoke to The Daily Telegraph after one of his branded minibuses was stopped en route to the airport on Sunday.

“There are all these documents you are supposed to carry. We obviously had them all but they should have been on the driver. It was the usual sort of 'good-cop-bad-cop’ [scenario]. It ended up as a fine of 135 euros [£112].”

Kinnear, who has lived in Megève for 25 years, says there is local bias, not just against the English, but against outsiders in general. “It is great being here, but we have a small number of Frenchman who have these social ideas in their bonnets,” he says. “It is not the majority, but the few. I know a few ski instructors out there who say to me it is not the English who they don’t like, but anybody who didn’t go to school in Megève.”

Yet the British snowsports market comprises more than one million active skiers, around half of whom ski in the Alps. Some resorts have been nearly taken over by English chalet-owners, hotels and restaurants.

In response, French officialdom has been devising schemes to stem the tide, such as banning British tour operators from taking guided groups out on the mountains.

Last year, a small British operator in Les Trois Vallées, Le Ski, was taken to court by the authorities over this issue – and lost. Liz Morgan, the co-owner and director, said an appeal was due within the next few months. “I don’t want to get into any French-bashing,” she says. “I speak fluent French and have a lot of French friends.”

She is not alone. Tom Watts, director of the British Alpine Ski and Snowboard School, which operates across the Alps, says his instructors – trained to French stipulations – enjoy a “fabulous relationship” with their Gallic counterparts. “If one of our children falls over, they would pick them up and bring them back to us and we would do the same for them,” he says. “There is no underlying French-British thing. That said, we don’t get invited around for a cup of tea or anything, we are competing for a similar business.”

The ski schools “work in a closed circuit”, says Mike Beaudet, a 64-year-old American who has taught in Megève for 20 years. “They will use exclusively English people or French people. What happens is there is no integration. I can think of two [English] companies that pay commission to get business – they pay English operators to do that. This could be responsible for some of the repercussions going on.”

He breaks off to regard the mountain slopes. “Megève is the last true bastion of the French, I suppose.”