Cells to hold newly arrested people could run out without the early prison release scheme, a government minister has said.

Bridget Phillipson defended the plan to address the prison capacity crisis in England and Wales by releasing thousands of prisoners early, which has been criticised by domestic abuse charities, bereaved families and probation officers among others.

“We have faced some really difficult and unpalatable choices because of the huge crisis that was left behind in the prisons estate,” the women and equalities minister told BBC Radio 4’s Today programme on Saturday.

She insisted the “most serious offenders” would not be released early under the scheme, details of which would be set out during the week.

“But the reality of what we are confronting is that, if allowed to go unchecked, we could end up in a position where someone who was arrested for very serious offences, for example, offences related to violence against a woman, and we wouldn’t have anywhere to send that individual. That was the full scale of the real crisis we face.”

Andy Burnham has been facing pressure to balance the competing aims of creating space in prisons and avoiding causing further upset to victims of serious crime. Under the scheme, a sentence would not be ended early but the portion of it served in custody would be shortened. The remainder would be served in the community, a principle that already exists in most sentences.

On Friday, families of those affected by homicide called for those convicted of any form of manslaughter to be excluded from the scheme. In a letter to the justice secretary, Alex Norris, they said they felt victims were “being asked to bear the consequences of the prison capacity crisis”.

Signatories included Emma Webber, whose son Barnaby was stabbed to death in Nottingham in 2023 and whose killer, Valdo Calocane, was convicted of manslaughter on the basis of diminished responsibility. Another was Diana Parkes, whose daughter Joanna Simpson was killed by her estranged husband, Robert Brown, in 2010. Brown was also convicted of manslaughter on the basis of diminished responsibility.

Phillipson said she had the “utmost respect and sympathy for the victims and their families” and blamed the previous Conservative government for allowing the prison capacity problem to fester. “We didn’t create enough prison capacity in the years that they were in government so that we don’t have to be even considering these kinds of options, which – in an ideal world – we would not be having to consider.”

In January, the government announced a set of measures, which came into force in March, that were designed to stave off a looming crisis this summer. Sources indicated, however, that these measures were never thought to be enough to avert further crises. They pointed to the Sentencing Act, which introduces wholesale changes to sentencing, as the government’s plan to fix the issue once and for all.