Clues that prisoners may take their own lives are too often missed, according to a stark warning issued by a watchdog.
Known factors indicating a heightened risk - such as a history of suicidal behaviour or the circumstances of their offence - can be overlooked, the Prisons and Probation Ombudsman (PPO) said.
The Press Association reported that Ombudsman Nigel Newcomen said: "The early days and weeks of custody are often a difficult time for prisoners and a period of particular vulnerability for those at risk of suicide.
"The Prison Service has introduced reception, first night and induction processes to help identify and reduce this risk.
"Some prisoners have obvious factors, such as mental ill-health or a lack of experience of prison, that indicate that they are at heightened risk of suicide, but my investigations too often find that staff have failed to recognise or act on them – with potentially fatal consequences."
The watchdog cited a number of cases including one in which a man charged with a violent offence was found hanged in his cell.
His family, probation officer and solicitor contacted the prison to alert staff about his risk of suicide.
The PPO said: "We were concerned that there were no clear reception procedures to ensure that staff working in reception understood their responsibilities.
"Not all the staff in reception saw all the information they needed to assess his risk, information was not shared and no one recorded his risk factors or the reasons they had decided not to begin ACCT (Assessment Care in Custody and Teamwork) procedures."
Too often staff in prison receptions make decisions based on their perceptions of an inmate's presentation and statements from the prisoner that they do not have any thoughts or intention of suicide or self-harm, the report added.
It listed a number of lessons to be learned including a need for staff to identify, record and act on all known risk factors during reception and inductions for all prisoners.
Figures show there were 89 apparent self-inflicted deaths in prison custody last year.
Frances Crook, Chief Executive of the Howard League for Penal Reform, said: "It is well known that people entering an institution are particularly vulnerable.
"It is therefore concerning that recommendations have to be repeated because they have not been acted on. Meanwhile, people are dying.
"We are waiting for bold action to address the prison crisis as the only way to save lives, reduce reoffending and make prisons safer is to reduce the number of people detained."
Juliet Lyon, director of the Prison Reform Trust, said: "The prison service has worked hard to improve its procedures, particularly in relation to first night, reception and induction, and had begun to succeed in making custody safer."
She added that "wider questions need to be asked about whether we are locking up too many vulnerable people in bleak, overcrowded and under-resourced institutions".
The news follows a previous review of self-inflicted deaths of prisoners which found that a significant number occurred in the first month in prison.
Last week David Cameron set out plans for wide-ranging reform of the prison system.
A Ministry of Justice spokesman said: "As the Prime Minister said last week, prisons are failing to treat prisoners' mental health problems as well as they should.
"If we fail to fix this issue, offenders will leave prison just as likely to commit crime - and create more victims - as when they arrived.
"That is why the Prime Minister announced an overhaul of how mental health is treated in prisons, giving governors a much greater say over what services their prisoners need and how the available budget is used."
Shadow prisons minister Jo Stevens said the Government must "wake up" to overcrowded, understaffed and violent prisons.
The Labour frontbencher said: "This report is the third warning the Tory Government has had on prison suicides from the PPO in as many years. It's time the Conservatives woke up and took action.
"Under the Tories prisons have become overcrowded, understaffed and violent, and the deeply troubling rise in suicides in prisons is an issue that David Cameron must tackle immediately.
"It is vital that prison staff are aware of risk factors and able to act on them early so it is worrying that it is too often still not the case. Ministers must urgently give mental health the priority it deserves."
Useful websites and helplines:
- Samaritans offers a listening service which is open 24 hours a day, on 116 123 (UK and ROI - this number is FREE to call and will not appear on your phone bill.)
- Mind, open Monday to Friday, 9am-6pm on 0300 123 3393
- Get Connected is a free advice service for people under 25. Call 0808 808 4994 or email: firstname.lastname@example.org
- HopeLine runs a confidential advice helpline if you are a young person at risk of suicide or are worried about a young person at risk of suicide. Mon-Fri 10-5pm and 7pm-10pm. Weekends 2pm-5pm on 0800 068 41 41