The Nigerian extremist group, Boko Haram, has released a new video showing the massacre of civilians in the Nigerian state of Gowza.

The video was sent to local journalist late last night and was not released on social media. The massacre appears to have taken place in a school hall or dormitory, with the room filled with dead bodies, some still twitching, on the floor, near the town of Bama.

The victims are predominantly adults and are described as "non-believers" by the Islamist group, whose name means "Western Education is Forbidden".

In a chilling statement, Boko Haram's leader Abubakr Shekau reportedly declares: "We have made sure the floor of this hall is turned red with blood, and this is how it is going to be in all future attacks and arrests of infidels."

The fanatical leader, who has become known for his ranting videos, says: "From now, killing, slaughtering, destructions and bombing will be our religious duty anywhere we invade."

Shekau goes on to state that, according to the Prophet Mohammed, prisoners should be detained and held under protection. However, the extremist leader claimed that the latest victims were not worthy of saving.

Speaking coldly to the camera, Shekau says: "We felt this is not the right time for us to keep prisoners; that is why we will continue to see that the grounds are crimsoned with the flowing blood of prisoners."

Since the radical insurgency went on the rampage in 2002, an estimated 1.6 million people have been displaced. Many civilians from the northern states, most notably Borno, have been caught up in fierce fighting between the Nigerian army and miliants from Boko Haram.

The group is predominantly based in the thick Sambisa forest in northeastern Nigeria, enabling the group to easily cross over the borders of neighbouring Chad, Cameroon and Niger.

Boko Haram rose to world prominence after they kidnapped over 200 schoolgirls from a school in Chibok. The Borno state town was left devastated and a world appeal, led by a number of celebrities including Michelle Obama, attempted to raise awareness of the kidnapped girls. Many of the girls remain in the hands of Boko Haram.