(CNN)Child migrants are being abused, detained and returned to Italy illegally by French police, according to a report published Friday by the charity Oxfam.
Some children trying to cross the border near the Italian coastal town of Ventimiglia have had their mobile phones seized and SIM cards stolen by the authorities, while others have been sent back to Italy after having had the soles of their shoes cut off, according to the report.
"French police officers are not upholding international standards," said Chiara Romagno from Oxfam Italy. "It's unacceptable. Besides pushing them back illegally, without offering any guarantees, against the law, they taunt them and mistreat them."
The French interior ministry did not respond to a request for comment from CNN.
Earlier this year, an administrative tribunal in Nice ruled that the police violated legislation in 20 separate cases of unaccompanied children who were detained and returned across the border to Italy.
But there is no indication yet that the treatment of migrants at the border is improving.
Since June 2015 -- when France first clamped down on its Italian border and sent armored vehicles to the frontier near Ventimiglia -- men, women and children trying to cross into France to claim asylum, rejoin family members or look for work have had little success.
In 2017, almost 23,000 people traveled through Ventimiglia. The figure in 2018 so far is 4,231, which is likely to increase rapidly as the weather improves, according to Oxfam.
One in four are unaccompanied children and the number of single women, vulnerable to abuse and trafficking, is increasing.