Prisoners kept in overcrowded jail cells in England and Wales are nearly 20% more likely to be involved in assaults, new research suggests.
The Ministry of Justice published analysis to better understand the link between violence and overcrowding in male and female adult prisons on Thursday.
Research of closed adult prisons in 2022 found inmates in overcrowded cells are 19% more likely to be involved in an assault over a one-year period, compared to those who stay in cells that are not overcrowded.
The document added the true figure is likely to lie between 15% and 24%.
The MoJ said this is the first time a direct link has been drawn between increased violence behind bars and the overcrowding crisis.
The findings come as the Government approved the use of protective body armour for prison staff in high security areas, after four prison officers were attacked with hot oil and homemade weapons by Manchester Arena bomb plotter Hashem Abedi at HMP Frankland in April.
Ministers have also accepted recommendations from the independent sentencing review to tackle overcrowding behind bars in the long-term.
Prisons minister Lord James Timpson said: “These stark findings confirm what we’ve already seen – dangerously full prisons lead to more crime and more violence.
“This not only risks the safety of our hardworking staff but means our prisons are failing one of their most important functions – cutting crime.”
Latest figures published in April show the number of assaults on staff in adult prisons in England and Wales per year has reached its highest level in a decade.
Some 10,605 assaults on staff in male and female jails were recorded in 2024, up from 9,204 in 2023 and nearly three times the 3,640 in 2014.
A total of 30,490 assaults of all kinds were also recorded in prisons last year, the highest number of assaults in a calendar year since 32,539 were recorded in 2018.
Ministers have vowed to create 14,000 new prison places by 2031, while plans under the sentencing review to curb overcrowding are hoped to take effect by next spring.
This includes changes where prisoners could be released earlier for good behaviour, or kept in longer if they do not comply with prison rules.
On Thursday, ministers also announced a £40 million cash boost to improve security on the prison estate, including to crack down on drones and contraband with reinforced windows, netting, CCTV and flood lighting.
The investment also comes as the National Crime Agency, collaborating with the prison service, National Police Chiefs’ Council and regional organised crime units, launched a new initiative to tackle drones smuggling contraband into jails.
Two senior police leads will also join the corruption and crime unit within the prison service to boost work such as organised crime behind bars.
Lord Timpson added: “We must end this chaos. Our £40 million new investment will also help combat the flow of contraband which creates unsafe environments in our jails.”
Latest figures show the prison population in England and Wales is 87,032, down by 1,489 below the record of 88,521, which was reached on September 6 last year.
