Hundreds of rehabilitated offenders will see an end to their long-abolished indefinite prison sentences under laws coming into force on Friday.

The change in rules will affect some criminals who were handed Imprisonment for Public Protection (IPP) sentences and mean their licence period comes to an end – giving them a defined finish date for their sentence for the first time.

IPP sentences were introduced in 2005 to prevent serious offenders who did not warrant a life sentence being released when they still posed a danger to the public.

Despite being scrapped in 2012 – which the Ministry of Justice (MoJ) previously said was “due to the inconsistent and more frequent application of these sentences than was intended” as it described them as “unjust and long-served” – 2,694 criminals remain behind bars after being given such a sentence.

Last year, then justice secretary Alex Chalk vowed to take “decisive action” to address the issue, which he described as a “stain on our justice system”.

Now the current prisons minister Lord Timpson said the latest move is a “significant step” in doing this.

But amid the overcrowding crisis in prisons, critics warned the work to release people serving IPP sentences was moving at a glacial pace.

Offenders released from prison on licence while serving an IPP sentence had to wait a minimum of 10 years before they could have their licence reviewed by the Parole Board.

The reforms mean licence conditions for 1,800 IPP offenders who were released from prison at least five years ago, but have not been sent back to jail within the last two years, will end immediately.

Those who were children when they were sentenced can have their licences terminated four years after their first release, provided they have not been recalled to prison within the last two years.

Another change, due to come into force in February, could see 600 more people serving such sentences having their licences ended as the time for the Parole Board to consider their case is cut from 10 years to three.

Any criminals serving an IPP sentence but still deemed a risk to the public will stay behind bars until the Parole Board recommends their release to “balance” protecting the public with the need to move offenders “who have turned their lives around out of prison and off licence”, according to the MoJ.

Richard Garside, director of the Centre for Crime and Justice Studies, said: “The Government claims it is working at pace on releasing IPP prisoners. Yet the rate of release of IPP prisoners remains glacially slow.

“Like many others, I welcome the changes to post-release supervision requirements for IPP prisoners, introduced by the previous Conservative government, which start coming into force on Friday.

“I also very much hope the Government keeps an open mind on the necessity for more urgent action if, as many fear, its current approach to resolving the IPP scandal falls short.”

Lord Timpson said: “It was absolutely right that the IPP sentence was abolished. It has left many ex-offenders subject to indefinite probation supervision long after turning their backs on crime.

“IPP offenders who have served their time in prison and lived safely in the community for years should not be subjected to a lifetime licence and today we have taken a significant step in addressing this.”