The latest official “safety in custody” statistics show that an epidemic of violence has swept prisons in the 12 months to September, with a 40 per cent rise in assaults on staff and a 28 per cent increase in prisoner-on-prisoner assaults. The rise in jail suicides has been accompanied by a 23 per cent increase in incidents of self-harm to 37,784.

The justice secretary, Elizabeth Truss, said: “Since becoming justice secretary, I have been clear that the violence, self-harm and deaths in our prisons are too high.

“I have taken immediate action to stabilise the estate by tackling the drugs, drones and phones that undermine security. We are also investing £100 million annually to boost the frontline by 2,500 officers.

“These are longstanding issues that will not be resolved in weeks or months but our wholescale reforms will lay the groundwork to transform our prisons, reduce reoffending and make our communities safer.”

The Royal College of Psychiatrists said the fact that prison suicides were at record levels was tragic, but it was only one of the most serious consequences of the last government’s decision to cut prison staffing while prisoner numbers were rising.

“The prison service is in crisis following a 40 per cent cut in the number of prison officers and mental health teams are struggling to help prisoners in desperate need. In many cases there is no one available to escort prisoners to in-prison clinics from time to time, even when a psychiatrist goes to a prisoner’s cell, as there are not enough prison officers present and the cell door can’t be unlocked for safety reasons,” said Professor Pamela Taylor, of the RCP’s’ forensic faculty.

“Training for staff is also suffering. Last week’s inquest into a prisoner’s suicide in Cheltenham reported that prison staff mistakenly believed ‘a prison psychiatrist’s’ permission was needed before he could be transferred to hospital. Health service staff can only do so much – the whole system must become more functional.”

The detailed figures show there were a record 354 deaths in prisons in 2016, up 97 (38 per cent) from the previous year reflecting the ageing profile of the prison population, particularly the conviction of sex offenders on lengthy sentences.

The record high of 119 self-inflicted deaths included 12 women prisoners. The justice ministry said the likelihood of self-inflicted death in custody was now 8.6 times higher than in the general population.

Assaults behind bars have also reached a record high of 25,049 in the 12 months to September, a rise of 31 per cent or 5,995 on the previous year. The figures include 3,372 assaults classed as serious – an increase of 26 per cent over the previous year. Serious assaults on staff have trebled since 2012, reaching 761 in the most recent year.