Boris Johnson’s pledges to create thousands of new prison places and boost security inside jails will not address an “enduring crisis of safety and decency”, MPs have found.

A scathing report by the House of Commons Justice Select Committee accused the government of making “policy by press release” announcements that do nothing to tackle long-term issues driving violence and reoffending.

Mr Johnson made crime a cornerstone of his early policymaking, swiftly announcing £100m for prison security and a £2.5bn programme to create 10,000 new places by 2023.

The government also plans to lengthen the time served inside jail by serious offenders by ending automatic release at the halfway point of most sentences.

But the Justice Committee said there was no “clear or coherent vision” for the system, or how to better rehabilitate the criminals inside it.

UK prison conditions: in pictures Show all 8 1 /8 UK prison conditions: in pictures UK prison conditions: in pictures A cell covered in graffiti at HMP Liverpool. PA UK prison conditions: in pictures HMP Liverpool has some of the worst conditions inspectors have seen. HM Inspectorate of Prisons/PA UK prison conditions: in pictures A broken window in a cell at HMP Liverpool HM Inspectorate of Prisons/PA Wire UK prison conditions: in pictures A shower unit with protruding electric cable at HMP Liverpool HM Inspectorate of Prisons/PA UK prison conditions: in pictures Litter at HMP Liverpool HM Inspectorate of Prisons/PA Wire UK prison conditions: in pictures A wall damaged by damp at HMP Liverpool HM Inspectorate of Prisons/PA UK prison conditions: in pictures A pool table at HMP Liverpool HM Inspectorate of Prisons/PA UK prison conditions: in pictures A sign for HMP Liverpool, where drones are seized at a rate of more than one a week. The prisons watchdog flagged up the impact of the remote-controlled flying devices at HMP Liverpool. PA

Chair Bob Neill said: “New prison places might be welcome, but they do nothing to improve the appalling condition of much of the current prison estate, nor the prospect of offering a safe environment in which to rehabilitate offenders.

“Prisons will not become less violent without proper investment in purposeful activity for prisoners to support rehabilitation.”

The latest official statistics show self-harm incidents at prisons in England and Wales rose by a quarter to a record high of 58,000 in the year to March.

In the same period, assaults rose by 11 per cent to 34,500 and attacks on staff were up 15 per cent to a record of 10,300.

The committee said the government must focus on ensuring prisoners carry out “purposeful activity” to reduce violence, cut reoffending and prepare them for re-entering society.

While the government has claimed that sentence increases would work as a deterrent, MPs said the announcements could increase overcrowding that has been linked to disorder and poor conditions.

Mr Neill said the government had a “poor track record in building prisons”, adding: “We want to see the detailed plans for the promised £2.5bn for 10,000 more places, what they’ll look like and when they’ll be up and running.”

Campaigners hit out at the policy when it was announced in August, saying that 9,000 places would be needed just to eliminate overcrowding.

Boris Johnson is suprised at how drugs and mobiles are smuggle during visit to Nottingham prison

The report found that the prisons estate in England and Wales was in an “appalling” state, with Victorian buildings and other ageing jails facing a £1bn maintenance backlog and seeing squalid conditions and vermin infestations.

“We are particularly concerned by the focus on creating additional places, rather than on replacing dilapidated and decrepit prisons in the current estate,” the committee said.

“Prisons should be safe and decent environments that rehabilitate offenders but this not currently the case.”

The report added that even when failures are found, jails are not given the extra funding and help they need, concluding: “There is little point in identifying poor performance if the necessary resources are not then provided to drive improvement.”

MPs said a long-term funding settlement was required to make jails safe, and for changes to how facilities’ management contracts are outsourced to private companies.

In 2017, the government increased the powers held by individual prison governors but the committee warned that there was no clear mechanism for accountability or clarity on what governors are responsible for.

The committee also repeated long-standing concerns about the recruitment and retention of prison officers, as a “high rate of attrition” leaves teams demoralised and lacking experience.

A Ministry of Justice spokesperson said: “We know that many prisons face challenges but we have been confronting those head-on by recruiting over 4,400 extra officers in the last three years.

“This government is investing tens of millions in security and improving conditions – an extra £156m for maintenance, £100m to ramp up security and tackle drugs issues, and £2.5bn to create 10,000 additional prison places.