More than 100 people have killed themselves in prisons in England and Wales so far this year, according to penal reform groups, prompting warnings of a mental health epidemic within the incarcerated population.

The Howard League for Penal Reform said it had been notified of the deaths by suicide of 102 people up until 18 November – the equivalent of one every three days and breaking the record for frequency of suicides.

“With five weeks remaining until the end of the year, it is already the highest death toll in a calendar year since recording practices began in 1978,” said Frances Crook, the director of the Howard League. “The previous high was in 2004 when 96 deaths by suicide were recorded.”

Crookwho is meeting the justice secretary, Elizabeth Truss, on Monday, said: “The number of people dying by suicide in prison has reached epidemic proportions. No one should be so desperate while in the care of the state that they take their own life and yet, every three days, a family is told that a loved one has died behind bars.

“By taking bold but sensible action 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.”

The current rate of self-inflicted deaths in prisons across England and Wales of nearly 10 a month means the final toll for 2016 could be as high as 115, compared with 89 in 2015.

A joint report, Preventing Prison Suicide by the Howard League and the Centre for Mental Health, links the rise in the number of prison suicides to cuts to staffing and budgets and the rise in the number of people in prison that has resulted in overcrowding.]

Prison deaths Prison deaths

“Violence has increased and safety has deteriorated. Prisoners are spending up to 23 hours a day locked in their cells, the imposition of prison punishments has increased and a more punitive daily regime was introduced in prisons at the same time as the number of deaths by suicide began to rise,” it says. “The prison suicide rate, at 120 deaths per 100,000 people, is about 10 times higher than the rate in the general population.”

The report calls for a recently revised incentives and earned privileges regime to be scrapped and for an undertaking that prisoners with mental health problems or at known risk of suicide should never be placed in solitary.

The Howard League’s figures show that the highest number of self-inflicted deaths – six – this year have been at Woodhill prison, Buckinghamshire, which is at the centre of a high court legal battle.

Mr Justice Lavender gave permission on Thursday for a judicial review case to be heard, saying that evidence of repeated failures to implement policies to prevent self-inflicted deaths at Woodhill could not be dismissed as “operational failures”.

It has also emerged that an independent monitoring board at Bedford prison, which has had four deaths so far this year, wrote “an urgent letter of concern” to the prisons minister about the “alarming rise in prisoners attempting to hang themselves” at the jail before its recent riot. They highlighted that staffing shortages were “beyond crisis point”.

An independent monitoring board report published on Monday into Bullingdon prison in Oxfordshire warns that inadequate staffing is also damaging morale and relationships with prisoners.

“The board is concerned about increasing difficulties in recruiting and retaining sufficient officers to maintain levels defined as acceptable by the prison service. It has also observed that indiscipline and violence have increased noticeably since staff cutbacks were implemented in 2013,” says the Bullingdon report.

The chancellor, Philip Hammond, confirmed in the autumn statement last week that an extra £555m over the next three years would be made available to fund prison safety measures, including the recruitment of 2,500 extra prison officers.

A Ministry of Justice spokesperson said that mental health in custody was taken extremely seriously: “Providing the right intervention and treatment is vital to improving the outcomes for people who are suffering and all prisons have established procedures in place to identify, manage and support people with mental health issues.

“But we recognise that more can be done. That is why have invested in specialist mental health training for prison officers, allocated more funding for prison safety and have launched a suicide and self-harm reduction project to address the increase in self-inflicted deaths and self-harm in our prisons.”