An official watchdog has hit out at a "lack of concerted and sustained action" following a jump in suicides among female prisoners.
Prisons and Probation Ombudsman Nigel Newcomen said lessons identified in a new review of cases had been highlighted previously by his office.
And he warned that sweeping reform envisaged a decade ago on the back of a review of the experiences of vulnerable women in the criminal justice system has yet to be delivered.
Self-inflicted deaths among women inmates have been on the increase, with 12 recorded last year - more than double the number in 2015.
On Tuesday, Mr Newcomen will publish a bulletin which examined 19 cases between 2013 and 2016.
The report says care from individual staff was often very good but it also highlights areas of "weak practice" and "basic failings".
There was a "clear theme" of poor joint working between mental health and custodial staff, according to the assessment.
It found that there were examples where risk was not handled appropriately and identified evidence of inappropriate use of punitive approaches to address instances of self-harm.
The paper re-emphasises a number of lessons for prisons, saying that many are a reminder of what already appears in their own rules and processes.
Mr Newcomen said: "I find it disheartening that many of the lessons we identify to prevent women in custody from taking their own lives repeat those in previous publications from my office.
"This suggests it is not knowledge that is the issue, but a lack of concerted and sustained action.
"While we often identify examples of excellent and compassionate care by individual staff, and also recognise that prisons have been under enormous strain in recent years, there can be no excuse for not implementing essential safety arrangements that could ensure vulnerable women are better protected.
"It is to be hoped that delivering safer outcomes for women (and men) in prison will be at the heart of the Government's new prison reform agenda, and that this bulletin can assist with this and help to reverse the unacceptable and tragic rise in self-inflicted deaths."
A Government spokeswoman said: "The safety of those in our custody is a priority and all prisons have procedures in place to support those at risk of committing self-harm or suicide.
"We have increased the support available to vulnerable offenders - especially during the first 24 hours in custody - and have invested more in mental health training for prison officers.
"More funding has been allocated to prison safety, and we have launched a suicide and self-harm reduction project to address the increase in self-inflicted deaths and self-harm in our prisons.
"We are also working closely with NHS England and Public Health England to improve mental health services for offenders at all points of the criminal justice system and to address these issues in our establishments."
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