Hacking group Anonymous has posted a video warning of an imminent attack on the online accounts run by members of terrorist cells.
After three days of bloodshed on the streets of Paris, the so-called 'hacktivist' group said the massacre at the offices of the Charlie Hebdo satirical magazine was an "attack on freedom of speech".
Warning they would "not permit" such attacks, the video labels the terrorists "cowards", adding: "We will find you and not leave you any rest,"
The video opens with a montage of images from the protests which followed the killings, before a member wearing the Anonymous' trademark Guy Fawkes mask addresses the "citizens of the world" in an electronically-distorted voice.
A new Twitter account, @OpCharlieHebdo, has also been set up urging users to report any websites suspected of terrorist affiliation.
They say by cutting off social media access - thought to be a major method of recruitment - they will reduce the number of jihadists.