In the wake of the Charlie Hebdo massacre in Paris last week, infamous online hacking group Anonymous has declared war on jihadists.

The ‘activist' group released a video on their Belgian YouTube account in which the members condemned the attack that left 12 people dead.

The video shows a figure wearing the standard Anonynous uniform of a black jumper and Guy Fawkes mask.

“We are declaring war against you, the terrorists,” the figure says in French in an electronically-distorted voice.

The figure says Anonmymous will ‘track down and close all accounts on social networks related to terrorists to avenge those who were killed' in the terrorist attack.

The group claimed on Saturday to have hacked the website ansar-alhaqq.net on Saturday afternoon, a French jihadist website.

In a post on Pastebin, the group says to “expect a massive frontal reaction from us because the struggle for the defense of those freedoms is the foundation of our movement.

Established in 2003, the elusive hacking group has been linked to several online attacks across the globe aimed at punishing governments for policies of which they don't approve. The hackers release videos where they are seen wearing Guy Fawkes masks.

The group became known for a series of well-publicised publicity stunts and distributed denial-of-service attacks, which consists of flooding a website with traffic, on government, religious, and corporate websites, as well as child pornography sits and the Klu Klux Klan. Later targets include corporations such as PayPal, MasterCard, Visa and Sony.

Dozens of people have been arrested for their involvement with Anonymous, in countries including the US, UK, Australia, the Netherlands, Spain, and Turkey.