Prisoners in UK prisons are brazenly mocking the justice system by filming themselves fighting, taking drugs and messing around - then posting the footage on Instagram, MailOnline can reveal.

Inmates shamelessly record themselves using mobile phones illegally smuggled into jails using weapons to threaten other prisoners and upload them to HMP TV3, an Instagram page for jail videos with nearly 22,000 followers.

In one, topless prisoners sporting Mohawk hairstyles – and with one holding a six inch blade - threaten a new arrival to HMP Risley in Warrington, Cheshire.

These two men with Mohawk - style hair were filmed threatening a third prisoner in HMP Risley in Warrington, Cheshire with one holding a six inch blade

This is a grab from a video which shows a prisoner in jail being attacked by other inmates

These three prisoners were filmed on a roof at HMP Portland. It has been viewed 8,000 times

A prisoner warns him: 'Soon as you land here lad you're going to get it, you little maggot. You're going to get opened up on site you little muppet.'

Prisoners laugh in the background on the film, viewed by over 13,000, as he went on: 'You're going to get marched, skerched and left in the dirt lads!'

A source told MailOnline: 'Some of our worst convicts – who are inside for committing some pretty heinous crimes - are posting daily videos to this Instagram account using illegal phones.

'They're fighting, doing drugs, rapping, talking about wanting a 'bitch' and generally breaking the law. They even film oblivious prison officers.

'What happened to locking these reprobates away from society for punishment and rehabilitation?

'They're giggling on the footage like they're a bunch of naughty schoolboys. But after the crimes they've committed it's not funny, it's absolutely outrageous.

'Thousands are watching these films, so there are loads of people out there who've seen what they're up to. Yet the authorities obviously don't have a clue.'

This clip reportedly shows a prisoner known as 'Scouse' smoking from a crack pipe

These images show two prisoners brawling in a bathroom in which they claim is HMP Fight

The men are later seen grappling on the ground during the brief Instagram video

In a shocking clip, an inmate nicknamed 'Twitch' says he 'wants bitches'.

He also admits that he is in jail for stabbing a friend while high on 'devil's dandruff' slang for cocaine - before warning that when he gets out, he'll 'stab him again'.

In another video seen 9,000 times a prisoner nicknamed 'Scouse' smokes on a crack pipe, lit from another man's cannabis spliff. Scouse then claps and and says: 'Big up HMP TV!'

A third film shows three prisoners on the roof of HMP Portland, on an island off the coast of Dorset, with their arms in the air, shouting: 'Yeah, go on. Freedom!'

Meanwhile another has two prisoners fighting in what they claim is a jail dubbed HMP Fights where one bangs another's head on the toilet wall and floor before drawing blood. Others fail in a bid to pull them apart, with one saying: 'Are you mad? This is game over lads.' Before another adds: 'Yeah, you're going to f*** him up.'

A Prison Service spokesperson said: 'This behaviour is unacceptable and we are working quickly to get this account taken down. Anyone found behaving this way can expect to spend significantly longer behind bars.

'We have invested £2 million to detect and block mobile phones to prevent them being used in the first place.'

Prisoners can receive an extra two years behind bars if they are caught in possession of a mobile phone.