Murderers and rapists are being released into the community without proper risk assessments being completed, a damning report has warned.
One unidentified prison changed its paperwork for releasing life-sentence prisoners on temporary licence so the section dealing with risk of harm to others was removed to "simplify the process", prison and probation inspectors said.
Risk assessments were not being completed adequately, basic elements were missing and there was "confusion" over who was responsible for completing them, the inspection of life-sentence prisoners found.
Despite this, Her Majesty's Inspectorate of Probation and HM Inspectorate of Prisons said only 2.2% of those sentenced to a mandatory life sentence and 4.8% of those serving other life sentences re-offend.
Chief Inspector of Probation Liz Calderbank said prison governors were "not being supplied with sufficient, accurate information" and in a small number of cases nor was the Parole Board, which determines whether prisoners can be safely released into the community. She said: "Assessments in many instances weren't being thorough enough and weren't being completed adequately. Often, quite basic elements were missing that you would have expected to be included."
She added: "We were shocked at the fact that there was a lack of clarity and confusion about who was responsible for completing risk assessments when in custody."
Life sentences can be handed to offenders for a range of offences including murder, manslaughter and rape. Although life-sentenced prisoners have committed the most serious crimes, most will be released at some point - the average time served on a mandatory life sentence in 2011 was 16 years.
Release on temporary licence, which can range from a few hours for visiting a wedding to spending time overnight in a location the prisoners intend to live in, was not underpinned by a robust risk assessment, the inspectors found. The quality of assessments and plans to manage the risk of harm the prisoner posed left "considerable room for improvement", they added.
Justice Minister Jeremy Wright said: "Though this is about a small group of offenders, it is essential we get it right to protect the public. This government is introducing significant reforms to offender management, including setting up a new National Probation Service staffed by experts in the field and dedicated to risk assessing and supervising our most serious offenders.
"We are also reviewing the way we carry out releases on temporary licence to learn lessons and see what changes are necessary. We need a process for people to be reintegrated into the community at the end of their sentence, but it needs to be right and it needs to be something the public has confidence in."