Prisons ‘will run out of space’ within 18 months despite Labour’s commitment to spend £10bn for 14,000 new places

The UK will run out of prison places within 18 months despite plans to build 14,000 new cells, a new report has suggested.

The stark warning came as the Ministry of Justice announced plans for four new prisons to be built by 2031.

“It’s still not enough”, Justice Secretary Shabana Mahmood acknowledged, despite the government’s pledge to ensure dangerous criminals can always be locked up over the next decade.

Official modelling published on Wednesday shows that in May 2026 there will be 89,800 prisoners but only 88,400 ­spaces in Britain’s jails.

Government estimates suggest more than 100,000 prisoners could be held in jails across England and Wales by 2029.

The planned expansion will only create 96,000 usable spaces, prompting the justice secretary to declare that “we are going to have to do things differently in this country”.

The government has pledged £2.3bn over the next two years towards building the new prison spaces.

Around 6,400 of the new cells will be located in newly constructed prisons.

The remaining places will come from building additional wings at existing facilities and refurbishing out-of-action cells.

However, the plans have sparked concerns about the potential impact on green belt land, with prisons set to be designated as sites of “national importance”.

Planning expert Rosie Pearson warned: “The green belt will not be safe, whatever caveats the government say they have put in place. It’s the biggest risk to the countryside since the 1930s.”

Mahmood said the review would ensure “there is always a prison place available for people that have to be locked up for reasons of public protection”.

The review will examine ways to help prisoners “turn their lives around so they don’t commit more crimes when they come out”, she added.

It is expected to consider replacing short-term prison sentences with community punishments, including curfews and ankle tagging.

The justice secretary has promised there will be no more emergency releases, stating: “I’m not going to do any more emergency releases of the kind, either at the beginning [of this parliament] or as the last Conservative government did.”

An additional £500m will be allocated for “vital building maintenance” across the prison estate.

The expansion strategy comes amid growing concerns about conditions in existing facilities.

Mahmood criticised the previous government’s approach, stating they “pretended they could send people away for longer and longer without building the prisons they promised”.

She claimed their prison building plans were “years delayed and nearly £5bn over budget” and had left prisons “on the edge of collapse”.

Opposition figures have criticised the government’s plans, with shadow justice secretary Robert Jenrick accusing Chancellor Rachel Reeves of funding “inflation-busting pay rises for her trade union paymasters, but not new prisons to keep the public safe”.

Charity leaders have warned that building more prisons alone won’t solve the crisis.

Pavan Dhaliwal, chief executive of Revolving Doors, said: “We cannot simply build our way out of this crisis, increasing prison capacity and improving the condition of the estate is necessary but must come hand in hand with the commitment to exploring alternatives to custody.”

The Howard League for Penal Reform suggested the money would be better spent on “securing an effective and responsive probation service”.

The Law Society called for matching investment in legal aid, the Crown Prosecution Service and courts to help reduce reoffending rates and tackle court backlogs.