Hidden cameras behind bars.

"We have live footage, no bullshit, live as it's unfolding." Prison riot mobile phone footage

A prison on fire, 600 inmates on the loose from their cells, and a band of prison officers desperately trying to contain a full-blown riot, all while footage of the violence is streamed live on social media.

"Who's got the keys man, who's got the keys blood?"

"Outta control mate, outta control." Rioting prisoners

This was not the scene from an action film blockbuster, it was frighteningly real.

"You could see staff were genuinely scared. You could see the fear in the face from everybody. Because the potential now for you to lose the jail was as real as it was going to get." Prison officer

The astonishing footage revealed a prison system at breaking point.

"They were filming to put it on social media so that they make the public aware - the way they were being treated in the prison, because nobody else is hearing them." Former prisoner

The riot, at a major prison in Britain, highlighted problems facing governments around the world, including in Australia: how to manage soaring prison populations driven by law and order debates and public demands for tougher sentencing.

"Prisons are in crisis. Violence continues to increase, but with so much violence, particularly assaults on staff, prisons are not under proper control and the risk of further riots must be substantial." Former head of the UK Prison Service

Using footage filmed by prisoners themselves in correctional facilities across the UK, the program reveals a system rife with drug use, violence and squalid living conditions.

"Cells were filthy. They were damp, they were dark, lavatories were blocked. There were rats, there were cockroaches." Chief prison inspector

The UK crisis has focused debate on the growing role of private companies in running prisons, among them global companies like G4S, which also operates in Australia.

"People just get lawless you know? Especially when there's not much staff around." Former prisoner

This revealing documentary opens a rare window into life behind bars and the pressures on those keeping watch.

"The government doesn't have a grip on the system and there's a cost in blood being paid." Former chief prison inspector

Prisons Uncovered, from Clover Films for ITV and presented by Sarah Ferguson.