France's state-run nursery and primary school sector is in the spotlight after a major investigation was launched into allegations of violence and abuse, both physical and sexual, at more than 100 institutions nationwide.

Nursery school is compulsory in France from age 3 and the allegations relate to the behavior of workers known as school monitors, who are recruited by local authorities rather than by the national education ministry or individual schools, who play a significant role in supervising children during breaks, at lunch, and in after-school care and clubs.

Parents had reportedly been making complaints about some of these workers, who are often hired without any formal qualifications, for some time, before the current scandal came to wider public attention.

Florian Lastelle, a lawyer representing three Paris families who have filed police complaints, said it was a "massive scandal … the state school system is a source of pride in this country, but unfortunately in France today it's not possible to say that the public service guarantees children's safety".

Laure Beccuau, a public prosecutor for Paris, said investigations had begun into 84 preschools, about 20 primary schools, and about 10 daycare centers.

Emmanuel Gregoire, who was elected mayor of Paris at the end of March and who has previously revealed that he suffered abuse as a youngster in an after-school program, has launched a 20-million-euro ($23.3 million) inquiry into what he called a "major dysfunction" among the city's school monitors.

Before the latest announcement revealing the full extent of the allegations, he told Le Monde newspaper: "If there was a collective mistake, it was to treat these incidents as isolated when in fact they point to a systemic risk, and perhaps even a systemic code of silence."

In a separate address to the Paris municipal council, he added: "I know there is a clear breakdown of trust in the state school system … but we will get there; we have no choice."

Barka Zerouali, the co-founder of a parents' collective called MeTooEcoles, a reference to the international 'MeToo' movement raising awareness of violence and mistreatment of adult women, told the France 24 news website that, for too long, family complaints had been dismissed.

"I fear it's only the beginning, because I know of many families who are yet to hear back from the authorities," she said. "We're not just angry – we're outraged. It feels like we've been talking to the wind."

Another parents support group, SOS Periscolaire, said it had received more than 600 testimonies about alleged abuse from all over the country. Its co-founder, Elisabeth Guthmann, expressed sympathy with after-school workers, saying it was essential that "this profession regains its meaning …there are many monitors who are caring and deeply committed to their work, and we support their call for greater recognition".