New footage released Tuesday by Amnesty International shows what appears to be graphic violence carried out by men who appear to be members of the state-sponsored militias, the Nigerian military and the Civilian Joint Task Force

The video, showing beatings and extrajudicial executions, comes from several incidents in the northeastern part of the country, and could serve as evidence of war crimes committed by the Nigerian forces, the agency said. Amnesty International Secretary General Salil Shetty condemned the gruesome video, saying:

This shocking new evidence is further proof of the appalling disregard for humanity in north-eastern Nigeria, where war crimes are being committed with abandon by all sides in the conflict."

One portion of the video shows what appears to be soldiers slitting the throats of detainees in Miduguri, the Borno capital, before discarding their bodies in a mass grave. The footage is dated March 14, 2014, and followed the military response to an attack on a military detention center in the city of Maiduguri by Islamist militant group Boko Haram—which the CJTF has been fighting since 2009—that same day.

Additional video footage uncovered by Amnesty International from July 23, 2013 shows the Nigerian military and the CJTF stripping men naked and beating them with machetes in an effort to determine if they were Boko Haram members. According to eyewitness accounts, 35 men were detained and driven away in trucks. Days later the men were brought back to the area, shot in groups, and left for dead. 

Boko Haram, which gained international notoriety after kidnapping some 250 schoolgirls in April, 2014 was designated as a terrorist group by the U.S. in 2013.

Shetty condemned Nigeria's military Tuesday for failing to honor human rights. 

Members of Boko Haram and other armed groups are responsible for a huge number of heinous crimes - like the abduction of the schoolgirls in Chibok more than three months ago - but the military are supposed to defend people, not to carry out further abuses themselves."

4,000 have died in fighting in northeastern Nigeria this year, the majority civilians. 

Warning: the following video footage contains extremely disturbing images of executions.