Separate footage, believed to have been compiled by prison gang members, showed them holding up human hearts in front of a camera.
About 60 inmates were killed in Manaus, sparking a deadly wave of violence that included the riots in Natal and another at a prison in Roraima state that claimed the lives of more than 30 people.
Prisoners have been filmed allegedly cooking the flesh of fellow inmates over a barbecue during a 10-day riot which has seen 26 men killed.
In the sick video the apparently cannibalistic lags gloat as they show off pieces of meat on a skewer over a bonfire, claiming they’re toasting the remains of a rival without even bothering to hide their faces.
The footage was recorded at Alcacuz Prison in the north eastern Brazilian city of Natal which is in the midst of a bloody riot as rival gangs attack each other.
The bodies of some prisoners have been returned to their loved ones with their heads missing after they were decapitated.
Only 22 victims of the horrific violence had been identified so far, with forensic experts still trying to determine who two heads, a forearm, an arm and a leg removed by the prison grounds belonged to.
But fears unidentified inmates whose partial remains had been removed from the prison had ended up in the stomachs of their rivals are not expected to dissipate until police regain full control of the jail.
The prisoners filmed preparing their barbecue were said to belong to an Amazon drug gang called the Family of the North and a Rio de Janeiro-based drugs gang called the Red Command.
The man whose meat they claimed to be barbecuing was said to be a member of the Sao Paulo-based PCC or First Capital Command which kept the peace for years with the Red Command before their loose alliance fell apart last year and resulted in a spate of prison killings.
One of the bare-chested inmates pictured in the video, who made no attempt to hide his face, shouted out repeatedly: “Churrasco do PCC” – Portuguese for “PCC Steak.”
Another, who was brandishing a machete-style knife and had several front teeth missing, said: “And this is only the beginning.”
Pointing towards the meat on a skewer, he added: “Today it was us and they paid.”
One of the men even made a V for Victory sign to the mobile phone being used to film the scene.
It was not clear if a group of men on a rooftop overlooking the bonfire were members of the same gang or rivals.
The violence has been blamed on a war between drugs gangs battling for control of the cocaine trade in Brazil which is a key trafficking route to Europe.
It is feared the final death toll from the riot at Alcacuz will reach 28 once authorities have regained full control of the prison and are able to confirm the number of victims