The French Council of the Muslim Faith (CFCM) says it is suing Facebook and YouTube for allowing the Christchurch gunman to livestream the mosque killings.
The council said it was suing the French branches of the two tech giants for "broadcasting a message with violent content abetting terrorism, or of a nature likely to seriously violate human dignity and liable to be seen by a minor". according to the complaint.
Facebook has responded, saying it quickly removed the live video that showed the killing of 50 people on March 15.
The livestream lasted 17 minutes with internet and social media giants left scrambling to pull copies of the videos from their platforms.
Days after the attack, copies of the video were still available on numerous websites.
The CFCM, which represents millions of Muslims in France, said Facebook took 29 minutes to pull the broadcast down.
In France, broadcasting messages with violent content abetting terrorism can be punished by three years' imprisonment and a €75,000 ($122,800) fine.
While major internet platforms have pledged to crack down on violent content, critics say not enough is being done to address the issue.
Meanwhile, NZ Privacy Commissioner John Edwards lashed out at Facebook's lack of response to the filming of the massacre, saying "your silence is an insult to our grief".
Edwards shared an email with the Herald that he sent to a number of Facebook executives on Friday.
It reads: "It would be very difficult for you and your colleagues to overestimate the growing frustration and anger here at Facebook's facilitation of and inability to mitigate the deep, deep pain and harm from the live-streamed massacre of our colleagues, family members and countrymen broadcast over your network.
"Your silence is an insult to our grief."
On Twitter on Friday, Edwards accused Facebook of ghosting him - or ignoring all communication.
Earlier that day, the Herald posted an article noting that a New Zealand hate group remained on Facebook - complete with images too offensive to publish.
The story prompted Edwards to post a reply on Twitter: "After your piece on Facebook's 15th birthday which contained critical quotes from me, senior execs got in touch to offer regular briefings. We VC'D [videoconferenced] Singapore & Washington DC on 8 March & committed to "keep communication channels open". Contact since 15/03 .... 0."
The Privacy Commissioner had hoped for communication from Facebook after the March 15 Christchurch shootings - especially given he had publicly demanded that the social network hand over account details to NZ Police of all people who had shared a copy of the gunman's video. Edwards says sharing the clip is an "egregious" violation of the victim's privacy, in violation of NZ's Privacy Act.
Sharing also contravenes our censorship laws. The gunman's video and manifesto have been rated "objectionable" by NZ's Chief Censor, meaning they are banned. Those who view or share them face a fine of up to $10,000 if they do so while ignorant of the rating, and up to $50,000 (or $100,000 for organisations) or jail of up to 14 years if they knowingly share the material. The rating and penalties apply from the moment the material was produced, not the time it was classified.
The social network did not respond to Edwards over his request to hand over names. But in an interview with the Herald, Facebook's VP for global policy Monika Bickert indicated it would not co-operate.