Britain cannot solely fix its problems with a lack of prison places by just building more prisons, the Justice Secretary has said, amid warnings that existing jails are “little more than human warehouses”.

Shabana Mahmood said she will publish a “realistic” plan later this week to build 14,000 spaces, but cautioned that “we simply cannot build out way out of this problem”.

Ms Mahmood said the Government’s independent review of sentencing would serve as a separate way of freeing up places.

We simply cannot build our way out of this problem

The shortage of available places for prisoners led to thousands being released early after spending 40% of their jail term behind bars.

There were warnings before the Government scheme, which began in September, that there were only 100 available spaces in men’s jails in England and Wales.

Ms Mahmood was asked by Conservative MP Patrick Spencer about whether tougher sentencing would go hand-in-hand with more capacity.

Speaking during justice questions in the House of Commons on Tuesday, she said: “I’m sure his constituents will also recognise that even with the new supply that we are building, we are still going to run out of prison places because the demand into the system is much higher than the building that is being planned.

“We simply cannot build our way out of this problem, so in order to make sure there’s always a prison place for the people that need to be locked up and that we never run out of prison places again, we do have to have an independent review of sentencing.”

Mr Spencer said: “I welcome what this Government is doing to increase prison capacity but what is the Secretary of State going to do on tougher sentencing?

“And I ask that because if she goes to my constituency of Central Suffolk and North Ipswich, she’ll be met with a tough gruff East Anglian accent that says ‘what’s the point of building prison places if you’re not going to use them?’”

The review on sentencing, which is being led by former Conservative MP and Lord Chancellor David Gauke, will consider tougher punishments outside of prison as a way to free up space.

It will report to the Lord Chancellor in Spring next year.

Ms Mahmood later referenced a National Audit Office which she said was “damning” on the Conservative government’s record on prison building.

She said: “It showed that their promise of 20,000 prison places by the mid-2020s was hollow.”

She added: “Later this week I will set out a realistic plan for building the 14,000 prison places that we need in my 10-year capacity strategy and I will ensure that our prisons are never left on the point of collapse again.”

It came as chairman of the Justice Committee Andy Slaughter said some of the UK’s existing prisons are “little more than a human warehouse”.

The Labour MP for Hammersmith and Chiswick said: “The condition, especially of our Victorian prisons, is not conducive to rehabilitation or preparation for life on release. The Government is pressing ahead with the construction of 20,000 new prison places, which their predecessor failed to honour.

“What thought in the design and operation of these major new prisons has been given to the training, education, addiction and mental health needs (of) inmates for whom prison is currently little more than a human warehouse?”

Justice minister Sir Nicholas Dakin replied: “Obviously these new prisons will be built with all the things he mentioned taken fully into account, and the Government is determined to put 14,000 places in place.”

Liberal Democrat MP Bobby Dean (Carshalton and Wallington) said a prisoner had written to him to tell him he had “made an attempt on his life” due to the “appalling conditions” at HMP Coldingley, adding there was a prevalence of “drugs, violence, discrimination and denial of access to healthcare” at the prison.

Sir Nicholas said the Government is “determined to ensure the best possible conditions in our prisons”.