Hundreds of survivors of crime are unaware that their perpetrators will be freed on Tuesday despite requests that this would not happen, the victims’ commissioner has claimed.

As the government prepares to release 1,700 offenders to ease overcrowding in prisons in England and Wales, Helen Newlove said some victims were “unaware of their offender’s release” and could not seek protective measures.

The claim comes hours after No 10 warned that prisoners must be released early or the country would face “unchecked criminality” because there would be nowhere to jail criminals.

Lady Newlove said: “From the beginning, I sought assurances that all impacted victims would be informed of any early release dates, affording them the opportunity to request protective measures.

“I understand this has not been possible in every case, leaving some victims unaware of their offender’s early release. While I recognise the challenges in reaching certain groups of victims, this is regrettable and must be addressed.”

Whitehall sources confirmed that a “sizeable minority” of victims had not been warned.

The release of offenders is expected to start from 8am from prisons across England and Wales. Prisons expected to release several dozen offenders each include Brixton, Humber, Berwyn and Risley.

Under the scheme, some offenders will be released after serving just 40% of their custodial term.

Downing Street acknowledged it was “incredibly difficult” for victims to know that the offenders were being released before completing their sentence.

A No 10 spokesperson said: “As the prime minister said this weekend, no prime minister should be in a position where there are not enough prison places.

“That is why we took the immediate decision that we did. And without doing so, prisons would have completely run out of places, and we faced unchecked criminality on our streets with police unable to make arrests.”

The policing minister, Diana Johnson, told the BBC: “For those who will be released tomorrow, probation have been working very hard to make sure that there are plans in place.

“People are released on licence and can be recalled if they commit further offences. So there’s a whole range of things that are already in place to make sure tomorrow goes as well as we can expect, but clearly nobody wants to be doing this.”

Perpetrators of serious violent offences, domestic abuse and sexual offences are supposed to be exempt from the scheme, called SDS40, but campaigners against domestic violence say the exemptions list is not comprehensive enough.

The charity Refuge has warned of the possibility of “grave repercussions”.

“Survivors may not even know when their perpetrators are being released, as the insufficient victim contact scheme only covers serious sexual or violent offences, where the offender receives a custodial sentence of 12 months or more,” the organisation said.

“An estimated 10% of cases that result in a 12-month or less sentence are related to domestic abuse. In a further 10% of cases, the offender has been flagged by probation for domestic abuse.”

Harriet Wistrich, the director of the Centre for Women’s Justice, said: “We are aware that a number of victims of domestic violence are extremely anxious about the proposed releases and while specific exclusions have been made for a range of specified domestic abuse offences, there is still a risk that some violent offenders will not be captured by these exclusions.

“In circumstances where there is significant underresourcing of probation services there will be real and legitimate fears from survivors that offenders who know where they live may not be adequately protected.”

Probation officers have been given as little as a week’s notice to prepare for the release of some offenders, amid concerns that many could struggle to find housing or adequate support.

Officers are usually given more than three months to prepare services to help monitor and rehabilitate a serious offender.

Martin Jones, the chief inspector of probation in England and Wales, said that late information about who was being released would place “huge additional pressures” on probation staff.

“The eternal optimist says that the scheme will go well. But the realist in me says that some of those released will go on to reoffend, and a small proportion of those will be serious offences,” he said.

In a further development, the prisons watchdog has published a highly critical annual report that found that many prisons are severely overcrowded and understaffed, with violence one of the most pressing concerns in more than a third of institutions.

Charlie Taylor, the chief inspector of prisons, said that of the 32 closed prisons inspected, 30 were rated poor or insufficiently good in the inspectorate’s assessment of purposeful activity.

“Rather than prisoners participating in activities or interventions to reduce their risk of reoffending and support their mental and physical health during their time behind bars, inspectors found a surge in illicit drug use, self-harm and violence,” the report said.

Violence was one of the most pressing concerns that inspectors raised in 14 of the 39 prisons and youth offenders’ institutions inspected. At Lowdham Grange in Nottinghamshire violence had increased by 55%.

Taylor said: “Early-release schemes provide welcome short-term breathing space, but our report highlights worrying shortfalls in work to prepare men in particular for release even without the added pressures these schemes impose, and they are not in themselves a solution to decades of underinvestment and inertia in a vital public protection service.

“Prisons must be equipped to deliver the work for which they were designed: to reduce the risk of further offences being committed and more victims of crime created.”