President Emmanuel Macron made the announcement on Tuesday, and Prime Minister Jean Castex later clarified that the measures would include random checks at the Swiss and possibly Spanish borders and seven-day quarantines.
Downhill skiing is effectively banned in France for the season to help contain the spread of Covid-19 after the government said last week that ski lifts would remain closed until January, even though resorts could otherwise operate.
Slopes are open in neighbouring Switzerland, tempting French winter sports lovers to cross the border from December 15th, when the current lockdown is set to be lifted.
“If there are countries that keep their resorts open, there will be controls to dissuade the French,” Macron told a news conference.
This was to avoid “creating a situation in which there is an imbalance with stations in France”, he said.
Prime Minister Jean Castex, in an interview on French TV Channel BFM on Wednesday morning, added: “We are going to set up a quarantine with the neighbouring authorities, there will be random checks at the border.
“You will be placed in quarantine for seven days and you will undergo tests.”
He added: “It's my duty to protect my fellow citizens, and if other countries don't have the same conception, that is their right.”
Germany and France have called for an EU-wide ban on skiing over Christmas, against strong opposition from Austria.
Italy and Spain have yet to decide. Switzerland – not an EU member, though it has strong ties to the bloc – has ignored calls to fall into line, much to the frustration of French officials.
“In Switzerland, we can go skiing, with protection plans in place,” Swiss Health Minister Alain Berset said last week.
France's ski resorts have been up in arms over the ban, saying the weeks around Christmas and New Year are crucial for their survival since they account for up to a quarter of their annual revenues.
France's winter sport sector says it generates some €11 billion in revenues per year and employs 120,000 people during the season.