This is the chilling moment two young offenders are seen wielding huge zombie knives from behind bars.
In terrifying footage posted on Snapchat, two inmates at Feltham Young Offender Institution, in west London, are seen unsheathing the deadly weapons before swinging them around.
Both lags are believed to have been released since the video was filmed last year in the exercise yard.
The disturbing nine-second video, taken on an illegally smuggled phone, was shared on Snapchat last week.
Other inmates can be heard jeering as the one filming shouts: 'My f sons, you know.'
Retired Met Police officer Norman Brennan condemned the video as 'outrageous', telling MailOnline: 'We've got a knife epidemic on the streets of Britain. We don't want to start that spreading into prisons otherwise we might as well all give up because prisons are meant to be safe and secure from these types of weapons.
'We don't want to start these knives getting in there, because it can only end in somebody being murdered or maimed.'
The Sun reports that both lags have since been released, with one recently sharing a video of him inhaling nitrous oxide.
It comes as the Government desperately tries to crackdown on zombie-style knives amid a horrific outbreak of violence on the streets of London.
In September last year, Daejaun Campbell was fatally stabbed in the leg with a suspected zombie knife. He screamed 'I'm 15, don't let me die' as he bled to death in Woolwich, south east London.
This is the disturbing moment two young offenders are seen wielding huge zombie knives from behind bars
In terrifying footage posted on Snapchat , two inmates at Feltham Young Offender Institution, in west London , are seen unsheathing the deadly weapons
In September last year, Daejaun Campbell (pictured) was fatally stabbed in the leg with a suspected zombie knife
Police said his murder was a 'stark and sobering reminder of the danger of zombie-style knives'.
Zombie-style knives were banned in England and Wales from September 24 2024.
The Government defines 'Zombie-style' as weapons which are over eight inches in length and often have a serrated edge, spikes or more than two sharp points.
Retired officer Mr Brennan, who was stabbed in the chest as he apprehended a robber at night during his career, told MailOnline: 'The Government's nonsense about banning zombie knives makes absolutely no difference to those that carry them, or want access to them, or use them to maim and kill other people.
'If that's not bad enough on the streets of Britain, it's even worse when those who have been put away because they're serious and dangerous offenders, putting the lives of prison officers and other prisoners at grave risk.
'One has to ask how they can get these knives into prisons. Prisons are meant to be places that are secure, ie. that people will go to prison and will not have access to drugs, mobile phones and zombie knives, and it appears in this video that whatever you want to get into a prison, you can.'
Mr Brennan speculated that a drone may have been used to drop off the zombie knives as it would have been 'almost impossible' to take them through the prison gates.
This year has also already seen the fatal stabbings of Kelyan Bokassa, 14, on a bus in Woolwich, and Thomas Taylor, 17, at Bedford bus station.
Retired Met Police officer Norman Brennan (pictured) condemned the video as 'outrageous'
One of the lags can be seen swinging the zombie knife around, while others around jeer
The Ministry of Justice has condemned the video and has launched an urgent investigation
The footage was filmed at the Feltham Young Offenders Institute (pictured) in west London
It comes after there were 225 knife murders in the year to June 2024, according to Office for National Statistics data.
HM Inspectorate of Prisons revealed Feltham YOI, which holds inmates aged 15 to 18, has the worst violence of any jail across England and Wales.
There were 410 violent incidents and 343 weapons found in the year to March 2024.
Staff have also reported struggling with attacks from inmates.
In one incident, a teenage Muslim convert who was jailed for plotting a music festival terror attack has reportedly stabbed 10 prison officers since being put behind bars.
A source told The Sun: 'The first attack happened in the reception area on the day he arrived at Feltham.
'He asked a guard if he was Muslim, and when he said 'No', stabbed him.
'Yet he's also allowed treats from the canteen, and loves Pringles. He's babied and mollycoddled.'
A Ministry of Justice spokesperson said: 'This is unacceptable behaviour. We take a zero tolerance approach to violence across the prison estate.
'An investigation has been launched into this old footage, which dates back to around a year ago.
'Anyone found guilty of wrongdoing will be punished, which could include extra time behind bars.'
