When Youssra's three-and-a-half-year-old son started nursery school, he really wanted his mum to come on a school trip. So she signed up to help out on a cinema visit. She buttoned the children's coats outside their classroom and accompanied them to the front hall. But there, she was stopped by the headteacher, who told her, in front of the baffled children: "You don't have the right to accompany the class because you're wearing a headscarf." She was told to remove her hijab, or basic Muslim head covering, because it was an affront to the secular French Republic. "I fought back," she says. "I brought up all the arguments about equality and freedom for all. But I was forced home, humiliated. The last thing I saw was my distressed son in tears. He didn't understand why I'd been made to leave."

The French charity worker is now part of the protest group Mamans Toutes Égales, or Mothers All Equal. Based in Montreuil outside Paris, it has blocked school coaches, boycotted outings and staged street demonstrations in protest at the growing number of mothers in headscarves being barred from school trips. "This is an attack on freedom and democracy in state schools. They seem to want to wipe Muslim women off the landscape," says Youssra, 36.

Almost 10 years after France banned girls from wearing veils in state schools in 2004 – along with other religious symbols such as crosses or turbans – the Muslim headscarf is once again being pushed to the top of French political debate. France was shaken by two nights of rioting and car-burning in the Paris suburb of Trappes at the weekend after a police identity check on a French woman wearing a niqab, or full-face Muslim veil, raised questions about Nicolas Sarkozy's controversial 2011 law banning the niqab from public places. But even before the Trappes riots shocked the political class, tension had been rising for months in France over the broader issue of Muslim headscarves, including the simple hijab. Far from the headscarf debate being the preserve of the French right, the current Socialist government was already considering tightening laws on standard headscarves, despite France having some of the hardest-hitting legislation on veils in Europe. The headscarf, a piece of fabric which one Socialist MP complained was a French "obsession", is still a major political issue in François Hollande's France. MPs are now considering passing a new, tighter law limiting the professions in which headscarves can be worn, including banning carers in private nurseries from wearing it in front of young children.

"The veil: the left wants its own law," ran a headline on the front page of the leftwing daily Libération in March. The debate is raging on several fronts. First, mothers in hijab petitioned the government about being excluded from school trips, to no avail. Then the focus turned to babies' nurseries after a high court ruled in March in favour of a woman it said was unfairly dismissed from her job in a private creche for wearing a headscarf. The judgment sparked a political frenzy. Intellectuals and politicians criticised the court for backing the woman and warned that headscarves worn in private childcare centres could be a danger to impressionable young children. Hollande said a new law was needed over whether religious symbols such as headscarves could be worn by staff in private creches, perhaps extending the law to other areas of the private sector. Tension has been heightened by recent violent attacks on women in headscarves in Argenteuil, a Paris suburb, where a pregnant woman who was attacked miscarried days later. Hundreds of protesters at a street demonstration in Argenteuil last month condemned the toxic nature of the debate around the veil, weeks before the Trappes riots. Islamophobic attacks in France more than doubled between 2011 and 2012– with women in headscarves the principal target, accounting for 77% of victims of physical or verbal attacks, according to the French Collective Against Islamophobia. After the attacks on veiled women in Argenteuil, the French Muslim Council warned: "Attacks on women in headscarves multiply around the time of each debate about the wearing of the Muslim veil."

French police stand guard in Trappes, a suburb of Paris, on 21 July 2013 after a riot broke out when officers carried out an identity check on a niqab-wearing woman and her husband. Photograph: Miguel Medina/AFP/Getty Images

"France is not like it used to be. When I was a child, there wasn't a problem. I was born here. I was accepted," says Yetto Souiriy, 37, a mother of five who had been barred from school trips with her son in Montreuil because of her headscarf. "France now seems to be stoking a kind of anger against Muslims. You hear of women having their headscarves pulled off at the market. Even parents at my child's school look at me differently since I was excluded from trips. I had a lot of hope for the left in France, but in terms of discrimination, nothing has changed. Even in shops, I've had people say: 'Take off your headscarf. You're only wearing it to be aggressive.'"

The French Republic is built on a strict separation of church and state, intended to foster equality for all private beliefs rather than stigmatise any religion. Secularism is one of the few issues that unites left, right and the far-right of Marine Le Pen. At the heart is the rule that any state worker in the public service must be impartial and neutral, and so cannot show their religious belief with an outward symbol such as a headscarf. Public-sector workers – from teachers to post office or train station staff – are prohibited from wearing the hijab, a visible cross, turban or Jewish kippa. This legislation, dating back 60 years, is set in stone. But difficulties are emerging under Hollande's presidency as some politicians and philosophers petition for the state rules to be extended to parts of the private sector, namely restricting the wearing of Muslim veils by carers in private nurseries and asking mothers to take off their headscarves if they help on school trips. That the debate is centred on young children and whether they should not be "exposed" to headscarves has made it seem all the more divisive.

Anissa Fathi, 34, stirs her coffee in a halal burger bar in Montreuil while her eldest son plays. She has three children. Since her eight-year-old second son's primary school barred her from helping on outings because of her headscarf, she worries about the impact on a new generation who have seen their mothers picked out and excluded in front of the class. "Children are not stupid. They understand. A lot of children who have been exposed to this treatment of their mothers have had psychological difficulties. My son would have fits of rage, he was self-harming and hitting his head against the wall at home because I couldn't go. Whenever the date of a school trip approached, he would be extremely anxious and in tears."

Fathi, who is French, remembers her own mother going on school trips in a headscarf without a problem. "Sometimes I think tolerance has gone backwards." Once stopped from accompanying a school library trip because of her hijab, she noticed another mother allowed on the trip was wearing a large, visible cross. "That mother backed me, saying: 'If they had asked, I would never have taken off my cross.'" Fathi says her problems didn't start with her son's school. She left her job in a private company after being told that her hijab was a safety risk while she operated a small sewing machine attaching labels to hospital sheets. She feels Muslims are unfairly targeted. "Since September 11th I haven't really felt comfortable going out on my own in a headscarf."

A speaker addresses a gathering in Paris in protest against the ban on veiled women at school. Photograph: Fred Dufour/AFP

There is no law that specifically bars mothers in headscarves from school trips – legal experts warn it would contravene European human rights legislation. Instead, after a Montreuil court upheld a school's right to bar a mother in a hijab from an outing in 2011, Sarkozy's education minister issued a memo in 2012 recommending schools uphold the "neutrality of public service" on school trips, meaning mothers in hijabs should take off their veils if they want to help on a picnic or gallery visit. The memo leaves schools free to decide for themselves, so some bar mothers in headscarves and others don't. Despite petitions from Muslim mothers, the memo has not been annulled by the Socialists. The current education department said it was not about excluding parents from trips but reminding them that neutrality applies when on school activities. Mothers said barring them from outings while at the same time allowing them to run school summer fete stands in their headscarves was absurd.

In 2008, Fatima Afif was dismissed from her job at a private creche, Baby Loup, in Chanteloup-Les-Vignes, north-west of Paris. Located in one of France's poorest towns, the creche was unique – open 24 hours, every day, to help single mothers with awkward working schedules, including nurses, police officers and waitresses. The creche sacked Afif for insubordination and misconduct. She argued that it was religious discrimination because she returned from parental leave wearing a headscarf. The creche had an internal rule book that banned religious symbols worn by any staff. After years of fighting through the lower courts, which all found against her, the French high court ruled in March this year that Afif was wrongfully dismissed as a result of "discrimination on the basis of religious conviction" and that private firms could not apply blanket bans against all staff wearing the hijab.

The effect was a political bombshell. Many politicians and intellectuals were up in arms at the decision, warning that headscarves must be kept out of creches. The Socialist interior minister, Manuel Valls, told parliament he "regretted" the court decision, which "undermined" secularism in France. The feminist philosopher Elisabeth Badinter and other leftwing intellectuals demanded tighter laws enforcing secularism to keep religious symbols such as headscarves out of private creches to protect children and ensure "neutrality". One lawyer for the creche spoke of the "danger" of the hijab to impressionable children. Baby Loup became a byword for a new debate about tighter laws on the veil. Hollande swiftly announced on TV that a new law on religious symbols such as Muslim headscarves was a "necessity". He said that when there is "contact with children" in a private creche there should be a similar approach to the state sector. He went further, suggesting that in private firms where there was "contact with the public" a law may also be needed to limit religious symbols.

The president quickly reactivated a consulting body, the Observatory on Secularism, which is expected to report back in the coming months on how to frame a new law restricting headscarves and religious symbols in private creches. Aware of the explosive potential of this public debate, Hollande called for "calm and constructive dialogue". In the political class, some questioned the initiative. François Lamy, junior minister for urban affairs, warned that for years French secularism was just being built on "laws banning things", resulting in "rifts" and cracks in society. The Socialist MP Christophe Caresche cautioned against the danger of the "recurring political debate on the wearing of the veil", saying that passing a new law would just "fan the flames" of a French identity crisis and lead to "exclusion".

In 2004, the French government's ban on veils in schools caused outrage among the country's Muslim population. Photograph: Pascal Rossignol/Reuters

Françoise Laborde, a senator for the Parti Radical de Gauche, who sits on the Observatory on Secularism, had previously proposed a law to restrict religious symbols worn by people working with children, including childminders who look after children in their own homes. France's high number of state-registered childminders – recently praised by Britain's Conservative party as something to emulate – includes many Muslim women. That their work might be limited on the basis of religious beliefs and clothing was controversial and caused a row on the left. Laborde recently told Libération she still believed in ensuring religious "neutrality" for private creches and childcare professionals. She said she was sceptical about whether the Muslim headscarf could be worn by women of their own free choice. "In a way, it's the same question as prostitution. There are choices which are non-choices."

Djamilia Latrèche, 50, an experienced childminder in Nanterre, west of Paris, who wears a headscarf, says there is a mood of dread and disappointment among childminders. "Currently, I look after three children from families of all beliefs, Christian to atheist. They have never minded about my headscarf. For childminders now, it feels like the state wants to question us about our religion in terms of being fit for the job. This is unfair, discriminatory and absurd. I feel I have to hide the few religious books in my apartment, hide my identity. I was really happy when the high court found in favour of the Baby Loup creche-worker over religious discrimination. But what worries me now is the government deliberately stirring things, creating divisions in society by pushing for new laws. It's sending the wrong message to a society which should be inclusive. What if I'm out with the children I mind and someone tries to pull off my headscarf or throw stones at me?"

Dounia Bouzar, a French anthropologist specialising in legislation concerning religious symbols, says current laws in France are already sufficient to deal with workplace issues around the headscarf. Currently, 94% of problems with religious symbols or practices in the private sector are settled through dialogue. On the consultation to produce a new headscarf law, she says: "I hope it won't just add to hatred of Muslims, or worse prejudice than today."

In a patterned headscarf, Hafida Ouhami was standing with her young son at a recent Paris demonstration for equal rights for mothers in hijabs. "I work in social services," she told me. "So I take off my headscarf each morning when I arrive at work, and put it back on again when I leave. It's a bit like taking off part of my personality, but that's the law. I'm uncomfortable about politicians now pushing a debate about whether headscarves should come off in private companies and for childminders. It feels like pushing things to the extreme. It feels as if we're not welcome to be ourselves anywhere."