On the third floor of a modern police station west of Paris, an alert sounds and one of four officers – three women and a man – seated around a block of desks begins typing. Somewhere in France or one of its overseas territories, someone is reporting a sexual assault, sexist harassment or discrimination to a 24-hour chatline.

The police station at Guyancourt, 20km from the capital is the heart of the French government’s #NeRienLaisserPasser (#Don’tLetAnythingGo) project, part of its response to the #MeToo movement and, say officials, the first online portal of its kind in the world.

“We’re dealing with sexual assaults including rapes and sexist harassment. It’s anonymous and confidential. Victims can still go to a police station or gendarmerie, but often this is difficult for them, especially if they are reporting a rape,” says Captain Sandrine Masson, head of the new unit, made up of 16 officers working in shifts around the clock, and a psychologist. “This is another way for victims to contact us, to have their voices heard without having to go to a police station in person.”

France was accused of being slow to wake up to the #MeToo movement sparked by the Harvey Weinstein scandal. When it did, some, including actress Catherine Deneuve, caused a national outcry by dismissing it as little more than Anglo-Saxon sexual puritanism. But the scale of the French riposte #Balancetonporc (#Squealonyourpig) made it clear that not everyone agreed with them. Several other French actresses, among them Juliette Binoche, Marion Cotillard, Isabelle Adjani and Eva Green, recounted their experiences of sexual harassment.

French president Emmanuel Macron, who shortly after becoming president in 2017 pledged to set up an online service for victims of “violence, harassment and discrimination”, has made good on his promise. The chatline went live last November shortly after the equality minister Marlène Schiappa, a feminist writer, oversaw new legislation introducing, among other measures, on-the-spot fines for “insulting, degrading or humiliating comments” in the street or on public transport. Since then, 447 fines have been issued under what was nicknamed the “wolf-whistle” law.

The chatline officers do not know who they are communicating with; in most cases they will never know. In the six months the service has been operating 2,500 people have been in touch but less than a third take the step of identifying themselves and reporting the perpetrator: of those who do, 70% are women and 21% are girls. The rest are men and boys.

The average “chat” is 54 minutes; the longest so far lasted two and a half hours. As the victim does not have to speak they can report an abuse even if the perpetrator is near by. There is also a “panic” button which shuts down the page and erases all trace of the conversation should the perpetrator appear.

Although it is anonymous, Masson says police can ask internet providers to trace the person who has contacted them if they feel they are in danger or considering suicide.

“After MeToo there were lots more reports of sexual abuse and rape. Whether this existed before, nobody can tell you,” says Masson.

“What we know for certain is that some of our chats relate to old facts that were not reported. These are people who needed to speak to someone before and couldn’t.

“We’ve also had cases of conjugal violence where the person has locked themselves in the bathroom or WC and cannot speak but they can take their phone and chat. Many say they feel guilty and we explain that they are not in any way at fault.”

Figures released by the French interior ministry show that about 93,000 women report a rape or attempted rape every year, 90% of whom know their attacker. Around 225,000 women are subject to physical or sexual violence within a relationship; an estimated one million women have suffered sexual harassment in a public space. Yet fewer than 10% report the crime or press charges.

Masson says if someone reports sexual harassment in a public place, the nearest police station is alerted to send out an officer to issue an on-the-spot fine.

“There was a lot of criticism when the sexist outrage law was put in place. They said, ‘What are they going to do? Is whistling at someone in the street really a crime? What a waste of time’. But we’ve had 447 fines already and when the law is better known there will be more.”

It may not be simple to catch someone persistently harassing in the street or the bus, but Masson believes the law is a serious deterrent.

“A fine of up to €350 will make people think again about their behaviour,” Masson says. “The fact that it’s an offence and there’s a fine to be paid at once can be very dissuasive.

Schiappa told MPs in April: “Many of you on these benches told us it would never work, that we would not be able to define offensive sexist behaviour. The figures showed the government action was efficient and would grow in its power. With this law, France has become the first country in the world to punish harassment in the streets with fines.”