Parents and 'cutters' have been jailed in France but concerns remain that parents go abroad – including to UK – for FGM

The girls were ready to leave for London on Eurostar when French police arrived at the school gate to take them into care and their parents into custody. It is doubtful the cousins, both six, had been told why they were crossing the Channel. But activists campaigning against female genital mutilation (FGM) told the Guardian they had learned that the parents were planning to have them "cut", and tipped off the police just in time.

"We had to stop them going," said Isabelle Gillette-Faye of the Gams movement. "We were alerted by a family friend who knew what the parents were planning and was against mutilation. But we didn't have much time. We heard about it on the Thursday and they were travelling on Saturday morning. It was a close thing."

The story demonstrates France's zero-tolerance towards FGM, a tough approach that has jailed about 100 people in dozens of high-profile cases.

FGM was defined as a crime under French law in 1983 with the threat of 10 years in prison, or up to 20 years for cutting a girl under the age of 15. Parents who oversaw FGM were declared "accomplices" to the crime. The law also applies to parents who send French-born children abroad to be cut by making it a crime no matter where it is carried out. The first conviction was secured in 1988 against a father and his two wives, who were given three-year suspended sentences. In 1991, a cutter was jailed for five years. Two years later a mother was jailed for the first time, given a three-year sentence, two of which were suspended.

Linda Weil-Curiel is a lawyer who has been working to bring the cutters and parents to justice. So far there have been about 40 trials, an increasing number of which have ended in prison sentences.

"At first the African communities didn't want parents prosecuted, but it's against the law and the law is the same for all," she said. "We explain to doctors the importance of examining all children. In that way they can check not just for FGM but for sexual abuse."

Dr Emmanuelle Piet says tiptoeing around religious or social traditions has no place in the FGM debate.

"I've seen what FGM does and frankly I don't give a damn about cultural sensibilities. It's more important to prevent a violent crime being committed against a child or woman.

"People talk of culture and tradition, but children have a fundamental human right not to be mutilated. It's racist to think otherwise. Can you imagine the outcry if this was happening to white, blonde girls?"

Piet works in the north-eastern Paris suburb of Bondy, in the gritty Seine-Saint-Denis department, where roughly a quarter of the 53,500 population was born outside of France – the vast majority in former French colonies in Africa. As a gynaecologist, Piet sees many of the mothers and children at the mother and infant protection service, which offers free healthcare to children from birth to six. Among her patients are women who have undergone FGM in former colonies, including Djibouti and Mali, where Unicef says, respectively, up to 93% and 89% of women are cut.

"I ask if they want the same for their own little girl. Women and girls with mutilated genitals are often deeply traumatised and angry. I can see the fear and pain on their faces even before I touch them."

Gillette-Faye said the London-bound family were from a culture where "cutting is so ingrained they think they are doing the best for their daughters".

"The parents were very cultured, educated, professional, but it was completely normal for them to mutilate their daughters," she said. "A girl who wasn't cut wasn't considered normal or pure."

She added: "The parents wouldn't admit why they were travelling to London but we were told they were heading for a private clinic where the girls would be cut."

French doctors, hospital staff and teachers in areas of high immigration from countries where it is prevalent are trained by anti-FGM organisations to spot cutting and encouraged to report it.

As a result, Weil-Curiel, Piet and Gillette-Faye say they have seen no new cases of FGM carried out in France for a considerable time.

"We have a triple approach, preventing through education, shaming with publicity and punishing. It seems to work," Weil-Curiel said. "We see girls who are cut before they come to France, but we have not seen anyone cut in France for a while.

"You can be reasonably sure that a girl being taken away 'on holiday' during the school term to a country where FGM is rife is going to be cut," said Gillette-Faye.

"If we think this is going to happen, we call in the parents and examine the children. We explain why FGM is a crime and warn that we have recorded the child with nothing missing, so if she comes back cut then they will be prosecuted."

Piet admits parents still find ways around the law, but remains sceptical that many send their girls to the UK.

"FGM used to be carried out mostly on infants. Now girls who have been born and educated in France are being sent back to their parents' country, when they finish primary school, where they are cut and forcibly married. They return before their 16th birthday pregnant.

"When they come to see me. They are veiled, they are terrified and they are traumatised. They seem to have lost all their French education and language. It's like they have just arrived in a foreign country.

"They don't want to talk about it. As with other forms of violence, the aggressor warns them not to say what has been done to them."

French campaigners likesuch as Gillette-Faye, Weil-Curiel and Piet are incredulous of, and angered by, Britain's failure to tackle FGM.

"You have a tradition of multiculturalism, but you cannot accept everything in the name of tolerance, and certainly not the abuse of girls through mutilation and forced marriage," said Gillette-Faye.

"You have to tell parents cutting is not acceptable and if they don't listen you threaten them with prosecution and jail. It works."

The French former justice minister Rachida Dati summed up France's attitude, saying: "This mutilation has no foundation in any religion, philosophy, culture or sociology. It is a serious and violent abuse of a female. It cannot be justified in any way. FGM is a crime."