Random border checks will be imposed to stop French holidaymakers going to ski in neighbouring Switzerland, Prime Minister Jean Castex has said.
France, in common with Germany and Italy, is shutting its ski lifts over Christmas to stop the spread of Covid-19, but Swiss slopes are already open.
The ski season at Christmas and the New Year is a vital part of the economy for many European countries
Mr Castex said it was his duty to protect fellow citizens.
"The conclusion you need to make is that 'I'm not going to Switzerland'," he told BFMTV on Wednesday, adding that anyone who did go would face quarantine on their return.
Who's opening and who isn't?
Several EU leaders have tried to co-ordinate plans ahead of Christmas.
However, Switzerland is not part of the European Union, and Austria and Spain are keen not to shut their slopes entirely.
That has left one French town hall on the Swiss border draping Swiss flags from its windows in protest at the French decision not to allow the ski lifts to run. Châtel is among a number of resorts on both sides of the border that make up the Portes du Soleil ski area.
Mayor Nicolas Rubin accused French leaders of failing to listen and consult. "We've got a problem with the French government which shuts the slopes a month before Christmas while our Swiss neighbours keep theirs open," he told French radio.
In Switzerland itself the situation is still unfolding. Alpine resorts want to minimise restrictions but the government will decide on Friday whether to impose a limit on visitors.
Austria on Wednesday announced that skiing would be allowed from 24 December.
However, Austrian hotels will stay closed until 7 January and quarantine requirements for people from countries with more than 100 cases per 100,000 - which include Germany and Italy - are likely to severely restrict visits from abroad.
Other EU countries are expected to set out their Covid plans for the coming weeks:
- Italy is aiming to limit travel between regions and also between municipalities over the Christmas and New Year break. Last week Prime Minister Giuseppe Conte said: "It's not possible to allow holidays on the snow, we can't afford it"
- Germany has already joined France in calling for a holiday ban on ski tourism
- But Spain is trying to reach an agreement on measures for its autonomous regions to be able to open safely over the festive period.
What the French PM said
"I'm doing my utmost to appeal to every colleague," Jean Castex said. "The Italian prime minister, the German chancellor and France are working together. The Spaniards and Swiss aren't going along with us, but diplomatic action is under way."
He said his intention was to protect French resorts as well as French citizens from coronavirus, so not only would checks be put in place on the border, but prefects in areas along the border could impose seven-day isolation while Covid testing took place.
France is hoping to reopen its ski slopes from 20 January but the prime minister says the aim for the next few weeks is to prevent an influx of visitors over the festive season.
Among the most notorious outbreaks during the last ski season was at the Austrian resort of Ischgl, where visitors from as many as 45 countries said they caught coronavirus. Authorities are facing possible compensation claims from thousands of people for failing to act fast enough.
The World Health Organization says the problem lies not so much in the nature of skiing but in travelling to the ski slopes and in mixing with other skiers afterwards.