Facebook was the most proactive, taking down 53 out of 156 messages or comments, while YouTube deleted just 16 out of 225 pieces of content signaled by the groups. Twitter pulled up the rear, erasing just eight out of 205 flagged tweets. The results demonstrate "an unwillingness to fight hatred on their platforms, in total contradiction with French laws and often their own terms and conditions," say the groups. While the three social networks aren't required to delete every single hateful comment, they must moderate such messages when reported.

Twitter's Damien Viel with French Prime Minister, Manuel Valls at Twitter's new Paris HQ. (Martin Bureau/AFP/Getty Images)

As Le Monde points out, Twitter's poor takedown performance is particularly embarrassing, as the site recently inaugurated its French headquarters in Paris with French Prime Minister Manuel Valls. Last year, Valls launched a "national fight against illegal content" on social networks, calling "anti-Semetic, racist speech" on social networks "unacceptable."

Unlike in the US, holocaust denial and other forms of hate speech are illegal in France and other European nations. In Germany, Facebook and Twitter recently agreed to delete the most serious forms of such content within 24 hours. However, in describing the difficulty for social networks to stay on top of prohibited content in France, Facebook said it deleted one particular image (related to the 2015 terrorist attacks) over 32,000 times.

However, the anti-racism associations point out that Facebook manages to "rigorously" take down any content with nudity or pornography. "This makes us question whether Facebook, which is modeled on an American vision of society, is willing to conform to the standards of the French community and legal system." Added SOS Racisme president Dominique Sopo, "these platforms seem more shocked by bare breasts, which are promptly censored, than by hate speech content against individuals or groups."