Activists protesting against the "excessive" number of holiday properties in Brittany warned Britons on Thursday to stop buying second homes in the region.
Squatters claiming that holiday home buyers are making rents unaffordable for locals have occupied about 10 properties in Brittany, according to activists.
Ewan Thébaud, a spokesman for a group called Dispac'h, which means "rebellion" in Breton, said British property owners were not being targeted "for now".
However, he added that resentment was likely to rise if Britons kept on buying holiday homes in the north-western French region.
"If they continue buying up more homes in Brittany, then it will become a problem as locals will feel as if their land is being stolen," Thébaud told the Daily Telegraph.
Dispac'h, which describes itself as a left-wing separatist movement, has plastered holiday homes with stickers and posters bearing the message: "Brittany is not a second home. Villages in ruins, the youth in exile."
Thébaud claimed holiday homes outnumbered year-round residences in some villages, which was threatening the survival of local communities.
"Our campaign at the moment is aimed mainly at properties along the coast, which tend to be owned by the wealthy. Most of the Britons who have second homes here have bought houses inland, so it doesn't really affect them. For now, it's more about the well-heeled Parisians," he said.
Thébaud added that most of the 10 properties occupied by squatters are believed to be owned by British companies, which he said had abandoned them. He declined to specify the locations.
He claimed that the firms may have bought the properties to claim state aid for refurbishment or to launder money.
"Most of the time local people are pleased to see these houses occupied as they have been left empty for years. These are not holiday homes whose owners come once or twice a year," Thébaud said.
He added that Dispac'h was not responsible for squatting "as a group", but added: "If young people want to do it, that's not our problem."
Sharon Jackson, who has lived in rural Brittany for 20 years said: "I haven't heard of anything like this in our area. I think it's more likely to be happening in towns on the coast like Saint Malo. Where we are it's peaceful and friendly."
About 14 per cent of properties in Brittany are second homes. Britons own more than any other nationality except the French themselves, local officials estimated, adding that exact figures were not available.
Roland Tabart, the mayor of Arzon, a village on the Brittany coast, said: "We're aware of this problem and we can solve it by bringing companies here. Once our young people have jobs with those companies, we'll build housing for them."
However, Thébaud dismissed the plan as "far-fetched".
It is not the first time that foreign homeowners have faced hostility in Brittany. In 2005, protests against British property owners erupted there.
But John Smith, 70, who lives in the village of Saint-Gilles-Vieux-Marché in western Brittany, said he had seen "no posters, no banners, no parades. People here are fabulous. If there was a problem with squatters, the gendarme and the town hall are very tough on this and they'd be turfed out before they could settle."