The number of suicides in prisons in England and Wales is at its highest for seven years, new figures show.
Eighty-two inmates killed themselves in 2014, up seven from the previous year, according to statistics compiled by the Howard League for Penal Reform.
The charity said the deaths were a "direct result of the cuts to the number of [prison] staff".
Prisons minister Andrew Selous said the Howard League was "deliberately misrepresenting the situation".
In total, 235 people died in prisons in England and Wales during 2014, according to the figures which have been collated by the Howard League via notifications from the MoJ about individual prison deaths.
They show that despite a successive drop in the average prison population for the last three years there has been, over that same time period, a continued rise in suicides.
Last year more than 120 prisoners died of natural causes, and a further 24 deaths are yet to be classified by authorities.
Frances Crook, the chief executive of the Howard League, said: "It is evident that people are dying as a direct result of the cuts to the number of staff, particularly more experienced staff, in every prison.
"The government has chosen to allow the prison population to increase whilst it cuts staff, and that has led to an increase in people dying by suicide."
The charity also found that four prisoners took their own lives in HMP Wandsworth in London, last year, and a further four killed themselves in HMP Elmley in Kent.
Danny Shaw, BBC home affairs correspondent
Suicides of prisoners have a devastating impact. Not just on family and friends, but also on prison officers who are responsible for monitoring those at risk and dealing with the aftermath.
In 2008, the number of self-inflicted deaths fell substantially and stabilised, with about 60 deaths a year, until 2013, when they went up sharply, rising again last year.
Is it a coincidence that the increase came at a time when staffing numbers decreased significantly?
Prison officers say they're sometimes so stretched they have less time to build relationships with inmates and help them through their low moments.
Other theories include the "fear factor" in prisons where bullying and violence has increased, and a sense of despair among the increasing number of offenders serving long or indeterminate sentences.
Some answers may lie in a review of prison suicides among young adults, by Lord Toby Harris. For the prison authorities his findings can't come soon enough.
Six other prisons each recorded three deaths by suicide during 2014, the figures suggested.
But Mr Selous accused the Howard League of manipulating the figures to suit their own campaigning purposes.
He added: "Every death in custody is a terrible tragedy. We remain focused on doing all we can to prevent them.
"[But] they are deliberately misrepresenting the situation in our prison for their own ends. This helps no-one - least of all the vulnerable individuals in prison."
In the chief inspector of prison's annual report for 2013-14 Nick Hardwick describes the rise in self-inflicted deaths as "of most concern".
But the report also indicates that the reasons for this rise could be varied.
It says: "What pushes an individual in despair over the edge will be different in every case. However, as reports from the prisons and probation ombudsman and coroners make clear, bullying is a factor in many cases."
The report also says that "resource" was part of the issue.
Since 2010 the number of prison officers, governors and support staff in public sector jails has fallen by 10,000, with half the jobs going in the past two years, according to MoJ figures.
There has also been a huge increase in the number of adult male offenders, up almost 5,000 since the coalition Government came to power, the BBC's home affairs correspondent Danny Shaw said.
Meanwhile, a separate report, from the Prisons and Probation Ombudsman, has called on the authorities to do more to prevent suicides among Romany Gypsy and Irish Travellers who are over-represented in the prison population.