Young migrants are being hidden and sheltered by French villagers near the Italian border, who sometimes help them to slip undetected into the country.
At least 150 residents of several villages in the Roya valley, northeast of the French Riviera coast, have taken African and Middle Eastern teenagers into their homes "for humanitarian reasons", local sources said.
Police arrested more than 36,000 migrants in the area last year, most of whom were sent back to Italy, prompting local people to form a support group called "Roya Citizenship".
One woman, identified only by the first name Sophie, said she had given shelter to two teenagers from Eritrea at her home in Saorge. "If the police come, I'll say they're underage," she told the newspaper Le Parisien.
Many of the migrants in the area hope to settle in Britain where they say they have relatives or friends.