A culture change is needed to halt the rising number of suicides in prisons, according to a new report.
Campaigners said a "profound" shift was needed to move from a primarily punitive approach to one centred around recovery, wellbeing and rehabilitation.
Staff shortages and a "toxic" working environment were highlighted in a paper published by Centre for Mental Health and the Howard League for Penal Reform.
It also noted increasing concern around drugs formerly known as legal highs.
Figures published last month showed there were a record 119 apparent suicides in prisons in England and Wales last year.
It means the rate of self-inflicted deaths has doubled since 2012, while there has also been a rise in self-harm incidents across the estate.
Frances Crook, chief executive of the Howard League for Penal Reform, said: "Overcrowding and understaffing in prisons is placing intolerable stress on staff and prisoners, and putting lives at risk.
"No one should be so desperate while in the care of the state that they take their own life.
"Staff who work in prisons should never feel so under pressure that they cannot stop and listen.
"As prison suicides reach record levels, it is time for action.
"By taking bold but sensible steps to reduce the number of people in prison, we can save lives and prevent more people being swept away into deeper currents of crime and despair."
Sarah Hughes, chief executive of Centre for Mental Health, said the research shows a new approach to suicide prevention is needed.
She added: "We need to bring about a culture change in prisons that puts safety top of the agenda, that understands the traumas both prisoners and staff too often live with, and that means people get the right help when they need it.
"Making the changes set out in our report will save lives and enhance the rehabilitation of all prisoners."
A Government spokeswoman said: "We are committed to making prisons places of safety and reform and giving prisoners the support and treatment they need to help turn their lives around.
"All prisons have established procedures in place to identify, manage and help prisoners with mental health issues.
"Increased support is now available to those at risk of self-harm or suicide, especially in the first 24 hours, and we have invested in mental health awareness training for staff.
"An internal inquiry is also under way looking at all deaths in custody in the last year, to further our understanding of why these events happen."
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