More than 220,000 women were sexually harassed on public transport in France over two years, the national crime statistics agency said in its first report on the subject, describing it as a "conservative estimate".
The Harvey Weinstein scandal in the United States has accelerated a rethink of attitudes toward sexual harassment in France, a country that cherishes its self-image as the land of seduction and romance.
"Although the public mostly focuses on domestic violence, sexual violence committed on the street, on public transport or in other public places is just as serious, and merits more attention," the report said.
France's National Observatory of Crime and Criminal Justice (ONDRP) found that 267,000 people – 85 percent of whom were women – were sexually harassed on public transport between 2014 and 2015, including kissing, groping, flashing and rape.
It is the first time the ONDRP, which publishes an annual survey on insecurity, has focused on sexual harassment on public transport.
Paris was voted the third most woman-friendly city in a Thomson Reuters Foundation survey published in October, and ranked fourth least risky for sexual violence.
But harassment remains prevalent, many said on social media.
"I was spat at, called a whore ... and one morning groped by two laughing men on a crowded metro," Siobhán Dowling said on Twitter, describing her time in Paris as a student.
"The level of everyday harassment was shocking."
Sexual harassment on public transport was worst for women in the Paris region, with reports of incidents seven times higher than in the rest of the country, the study found.
Most cases of sexual harassment occurred when a train or bus was moving so the victim could not flee, the study said.
"When you have closed spaces with hundreds of thousands of people and zero security agents or police, it's no wonder that cowardly perpetrators act in total impunity," Ikram Moustaoui said on Facebook.
French women have taken to social media to share tales of sexual harassment, outstripping the #MeToo campaign with a name-and-shame hashtag #BalanceTonPorc - or 'expose your pig'.
French President Emmanuel Macron unveiled measures in November aimed at educating the public and schoolchildren about sexism and violence against women and improving police support for victims. He also proposed criminalising street harassment.
France's gender equality ministry declined to comment.
