Mental health services are in "free fall" at a time when the demand for services was never greater, according to the Psychiatric Nurses' Association (PNA).
In a report prepared for the HSE and the Minister for Health, the union says this is because of the huge numbers of psychiatric nurses retiring who are not being replaced due to the moratorium on recruitment.
It also blamed the small proportion of the health budget being spent on mental health in Ireland, which, at 5.3 per cent of the overall health budget, it is less than half the 12 per cent spent in the United Kingdom.
At the same time, demands on the service are increasing with rates of suicide going up and numbers presenting for treatment of deliberate self-harm rising.
The report says 596 psychiatric nurses retired last year and this has resulted in large number of posts remaining vacant.
Costly agency nurses are in some instances being used to fill gaps, "pushing services over budget, leading to further cutbacks", while in other instances "security companies are being employed" to care for patients in Ennis, Naas and Dublin.
It adds that in tandem with increasing numbers of vacancies in the sector, assaults on staff are rising. Some 1,314 assaults on staff were recorded last year, up from 966 in 2007 and 1104 in 2008. "While all these figures are probably understated they do point to an upward trend in assaults in a time period where staffing numbers are reducing".
On one occasion eight gardaí in riot gear had to come to the assistance of nurses trying to manage a highly aggressive patient, the report says.
The PNA said it was satisfied the need to employ security personnel and the increasing need to call for Garda assistance was not just related to an increasingly violent society but to shortages of nursing staff, retirements, reduced recruitment and reduced access to secure facilities.
Giving examples of recent incidents the report says: "On Sunday night last a patient set fire to part of the acute unit in Tallaght Hospital. A number of nurses were injured in the evacuation of patients with burns and smoke inhalation. A week earlier a patient, transferred from Cloverhill prison broke his way into the ceiling of the acute unit in Tallaght Hospital and accessed electric wiring which he wrapped around himself. When nurses got him down he was threatening and assaultative".
The PNA also said in Dublin north managers have announced the withdrawal of community based nurses to fill vacancies in hospital based mental health services. "The Government talks about transferring services from hospital to community but on the ground, because of Government policy, managers are doing the opposite," it adds.
Des Kavanagh, general secretary of the PNA, said up to 250 more psychiatric nurses were due to retire this year, and he has concluded psychiatric nursing must be exempted from the recruitment moratorium. "Staff shortages are contributing to unsafe and unsatisfactory experiences for patients," he added.
He also said psychiatric nursing contributed more than 40 per cent to the entire job cuts in the HSE last year, which showed the impact of the moratorium "is inappropriate and disproportionate".
In response, the HSE said the numbers of mental health nurses leaving over the past year could be in part attributed to their eligibility for early retirement at 55. It said 89 per cent of psychiatric nurses retire when they reach that age.
The HSE said the recruitment moratorium and reduction in psychiatric nursing staff had created a "significant challenge" but added it had secured a Government exemption from the moratorium targeted at the replacement of 100 psychiatric nurses this year.