Shocking footage has emerged showing "prisoners" being tied up stark naked and made to fight like dogs over "zombie drug" spice.
The video, allegedly filmed inside Forest Bank prison, in Swinton, Greater Manchester, shows the two men making feral noises and attempting to bite each other.
However, the fact the bullying men are dressed in branded, casual clothes, coupled with the presence of domestic items such as laptops and coffee flasks casts doubt over the location of filming.
Each of the "dogs" has a balaclava-clad handler who is holding them on a makeshift lead, pulling them out for a rest at regular intervals.
The cannabis synthetic is putting severe pressure on the prison system, with hundreds of inmates taking the drug, leading to assaults and ambulance call-outs.
As he introduces one of the competitors, a man says to the camera: "This is my Islamic, Turkey lurcher-pitbull."
The man on the end of the lead then starts making barking noises, before his opponent is introduced as: "The Iranian, one-eyed sausage dog."
He makes similar grunting sounds and lurches violently towards the camera as he attempts to follow commands as accurately as possible, reports the Daily Mail.
Both men, who are wearing makeshift tails, are then made to sniff each other's rears as part of embarrassing pantomime.
One of the men instigating the fight then says: "We're going to introduce one of these animals to draw blood. Now, the fittest dog is going to win."
The stark naked pair go at each other for around a minute before they are spared any further indignity.
A source told the Daily Star on Sunday: "It shouldn't be happening but it is - every day. The system is in utter chaos.
"There's not enough staff to stop appalling things like this happening and the ones that are here are busy attending to other spiceheads who have collapsed because they have had too much. It's totally out of control."
Forest Bank prison is a Category B jail with almost 1,500 inmates, and is run by private firm Sodexo.