REUTERS/Stephen Lam
The two associations, along with gay rights organisation SOS homophobie, analysed over a period of little over a month, 586 posts.
According to the findings, only 4% of those flagged posts were deleted from Twitter, 7% from YouTube, and 34% from Facebook.
SOS Racisme and the UEJF will sue the three American companies for not respecting French law, which requires web hosts to delete, in a reasonable period of time, posts which contain illicit content, and to send them to the authorities.
The organisations hope to shed light on how moderation works on the social media sites and to gain a global assessment of the companies' activities.
Sacha Reingewirtz, President of the UEJF, said in a statement that the social media sites had to comply with French law and that "the mystery that shrouds the social media's moderation teams operations prevents any serious progress in the diminishing of racist and antisemitic messages. Since such big platforms neither respect the French law nor their own terms of use, they will have to face justice."