As of 23 May, some male prisoners will now be freed up to 70 days before the end of their sentence in order to free up space, under the End of Custody Supervised License scheme.

Originally - it was 18 days, later extended to between 35 and 60 days.

In an email sent to prison and probation officers informing them of the extension, seen by Sky News, staff were told that "despite the push" and efforts of the scheme in previous months, that "pressures continue" in male prisons, and so further extensions to this emergency scheme are necessary.

"Everyone is having a disservice done to them here", a source close to the scheme, working in the probation service, told Sky News.

"The probation service can't cope with the additional workload this will result in. The scheme is already not delivering. The offender will not get the support they need. And the victim is being dealt an absolute disservice too."

Sex offenders, terrorists and category A prisoners, plus those serving four years or more, are excluded and aren't eligible for release.

However, sources close to the service have expressed concern about the extent to which the scheme is being amended, at pace, and often with little warning.

They say they have fears such extensions make releases unsafe - in some cases meaning prisoners are released without permanent accommodation, as housing places are meticulously planned with little margin to amend at short notice.

Without a home, some offenders cannot be fitted with the appropriate location monitoring tags.

A new report published on Wednesday by the Chief Inspector of Prisons, Charlie Taylor, highlighted implementation problems with the scheme in their inspection of Chelmsford Prison.

"We came across some prisoners who had been released homeless who had been recalled to the jail after just a few days," the report said.

It noted release dates being brought forward at "short notice" under the scheme, leaving resettlement providers insufficient notice to find appropriate housing.

"Astonishingly, having no fixed abode was not an exclusion within the scheme, and some prisoners had been released despite knowing they had no address to go to, only to make a swift return back to custody within a matter of days," it said.

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Nicole Jacobs, the UK's domestic abuse commissioner, has previously asked the government for an exemption for domestic abuse and stalk perpetrators - warning the scheme puts victims at risk.

Others suggest much broader reform is necessary in order to reduce the prison population.

"This is patchwork policy", said Steve Gillan, general secretary of the Prison Officers Association. "It won't have any impact whatsoever. As fast as they're releasing them, the courts are locking them up."

The prison service is under pressure.

Figures published on Friday showed 87,505 people are currently behind bars in England and Wales.

The number of people that can be held in "safe and decent accommodation" in prison, known as the "certified normal accommodation" or "uncrowded capacity", is considered by the Ministry of Justice (MoJ) to be 79,507.

That means the current overall system is at 110% capacity, or overcrowded.

Labour has accused the government of not being transparent about the policy.

"The Tories have once again used a cloak of secrecy to hide their early release of violent criminals", the shadow justice secretary Shabana Mahmood has said.

"The Conservatives' cover-up of this early release scheme is unprecedented. They are still refusing to answer how many prisoners have been released early, which prisons are using the scheme, and which types of offenders are being put back on our streets.

"This is a national scandal."

The government insists this is a temporary measure to relieve capacity in prisons, but Sky News disclosed leaked documents in February which revealed intentions for it to last for an "undefined" period.

It was "updated" and "revised" to apply in new prisons.

In March, Justice Secretary Alex Chalk told MPs that the measure will remain under review.

In a statement, a Ministry of Justice spokesperson said: "We will always ensure there is enough capacity to keep dangerous offenders behind bars.

"To ease the short-term pressures on prisons, in March we announced an increase in the number of days governors could, under existing powers, move some offenders at the end of their prison term on to licence. These offenders will continue to be supervised under strict conditions such as tagging and curfews."