The hacker group Anonymous has apparently responded to the attacks on Paris by posting a video declaration of war against ISIS.

In the as-yet-unverified video, posted on YouTube, a spokesperson wearing the group's signature Guy Fawkes mask said the group of hackers would use its expertise to wage "war" on the militant group.

"Expect massive cyber attacks. War is declared. Get prepared," the announcer says in French.

"Anonymous from all over the world will hunt you down. You should know that we will find you and we will not let you go. We will launch the biggest operation ever against you," the spokesperson continued, according to translated transcripts of the video.

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ISIS operates in parts of Syria and Iraq in its mission to establish a caliphate, but has recently orchestrated more attacks abroad, the latest being Friday's attack on various bars, restaurants and a concert hall venue in Paris.

A manhunt has begun in Europe to find those that helped the attackers, most of whom wore suicide belts. France retaliated at the weekend by launching more airstrikes against ISIS positions in Syria.

In Anonymous' latest video, the masked spokesperson says in French that "the French people are stronger than you and will come out of this atrocity even stronger," although the video was not on the group's official channel.

However, a tweet from the group's official Twitter account on Sunday said the group was at war with Daesh, — another name for ISIS.

The hacker group rose to prominence after a series of cyber attacks against individuals, governments and organizations that it does not approve of, including PayPal, Mastercard and the Church of Scientology, among numerous others.

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