The scenes of dozens of high school students kneeling behind their backs during the massive arrests carried out by the French authorities have raised Friday's denunciations as the country prepares for a new wave of violence during the upcoming Saturday protests of the "yellow jackets" protestors.
Left-wing politicians were angered by video recordings on social media of a young woman bending as riot police shouted in their faces.
"Nothing justifies the degrading image of the young boys," wrote the Socialist leader, Eulvier Faure, on Twitter. "There is no need to pour more oil into the fire."
The students were arrested Thursday in the Paris suburb of Mant-la-Jolie as part of the unrest that swept dozens of schools during three weeks of anti-government protests.
A total of 146 people were arrested outside the San Ixopri secondary school in the town after protesters clashed with police and burned two cars.
Laurent San Martin, a senior member of the ruling Republican Party, said some 40 students were hooded and carrying equipment that could be used for vandalism and burning; but he also described the footage as "shocking." He told France Info radio: "People have a right to be angry at these scenes."
The demonstrations, which came out of about 280 schools to protest the tougher entry requirements for universities, intensified the uprising in France as the "yellow jackets" movement continues.
Dozens of people, wearing masks, threw Molotov cocktails and set fire to rubbish bins and clashed with police outside schools in several cities on Thursday.
Close Paris
"Yellow jackets" peaked in Paris at the end of last week, with the worst riots in decades.
The protests began on 17 November to protest the increase in fuel taxes; however, they turned into a major movement against President Emmanuel Macaron and the biggest challenge facing his mandate.
The protesters are angered by the rising cost of living caused by high taxes, and they accuse the former banker of applying policies favoring the rich.
Demonstrators, mostly from rural areas and small towns, say Macaron is isolated from ordinary citizens and is demanding his resignation.
Farmers also called for daily demonstrations next week, while two truck drivers' unions are planning an open strike in solidarity with protests from Sunday evening.
Four people were killed in "yellow jackets" incidents, while political leaders from all walks of life called for calm, but many "yellow jackets" activists called for new weekend demonstrations, saying the government's concessions so far were insufficient.