French far-right leader Marine Le Pen has called for an end to free education for the children of illegal immigrants.
In a speech in Paris, the National Front's candidate in the 2017 presidential race next spring said she had nothing against foreigners.
"But I tell them: if you come to our country don't expect to be taken care of, to be looked after, that your children will be educated without charge," she said.
"No more playtime," she added.
Ms Le Pen is widely expected to be one of two candidates to reach the second and final round of the election in May.
Latest opinion polls suggest she is running neck-and-neck in polling for the first round with the centre-right candidate Francois Fillon, who was selected in national primaries at the end of November. The Socialists will hold their own primaries next month.
However, around two-thirds of voters would choose Mr Fillon over Ms Le Pen in the deciding round.
Ms Le Pen had been widely reported as saying the education ban should apply to foreigners, but after her speech she clarified to the AFP that she was talking about illegal immigrants.
However, she also said that foreigners using the state education system must be living in France legally and contributing to the tax system.
Cutting immigration has long been a bedrock policy of the FN, and Ms Le Pen has campaigned hard to cut legal immigration dramatically to 10,000 people a year, and to halt the right to family reunions.
Education has also been a central theme for the far-right leader. In 2014, she spoke out against providing substitute meals for pork dinners in schools for Muslims and Jews.
However under French law dating back to 1881, free primary education is a basic right for all children. The right to education is also a fundamental tenet of the European Convention on Human Rights.
French Education Secretary Najat Belkacem said in a blog entry that Ms Le Pen had not only demonstrated total indifference to the terrible plight of many migrant children, she showed the same level of ignorance of fundamental French values and laws.
Since she took over the running of the FN from her father almost six years ago, Marine Le Pen has worked hard to detoxify the party's extremist image and attract mainstream voters.
Her presidential campaign bears no trace of the party name and features a blue rose, borrowing imagery from both left and right.
But Ms Le Pen has had to respond to Mr Fillon's election as candidate by setting out distinctive policies.
On Wednesday, she accused him of being in hock to France's business organisation Medef, the European Commission, the banks and German Finance Minister Wolfgang Schaeuble.
In a live interview on Wednesday on one of France's main TV channels, TF1, she suggested she would put France back together in five years.
"I want to sort out the schools, France's diplomacy and the economy" she said, adding that she wanted a referendum on France's membership of the European Union.