General Secretary of the Psychiatric Nurses Association Peter Hughes has said the issue of recruitment and retention in psychiatric nursing is escalating on a monthly basis.
Speaking on RTÉ's Morning Ireland, Mr Hughes said that the level of vacancies is "totally unsustainable" and is seriously impacting on patient care and safety.
"The mental health services are very very reliant on overtime and agency staff, with a huge spend, there is €1m a week spent on agency cost and €300,000 a week on overtime, and our members are very frustrated because this is impacting on patient care and safety."
He said that the recruitment and retention of nurses within the Irish healthcare system needs to be addressed with "realistic" proposals from Government as a matter of "extreme urgency".
Mr Hughes also said the recruitment and retention issue could be resolved if entry-level nurses were paid on a parity with therapy grade staff.
He said that after a four-year degree, entry-level psychiatric nurses are offered a salary of €29,700, which is €6,000 less than for entry-level occupational therapists or play therapists.
He said that therapy grade staff work two hours less a week and earn more, although both grades enter service after completing a four-year honours degree.
Due to the low pay, he said students upon graduation looked to work for agencies, where they get paid more, rather than for the HSE.
He said market forces are also taking nurses to the UK, Australia and Canada.
Mr Hughes said psychiatric nurses would do their utmost to ensure their industrial action would not impact patients, though he said the understaffing and lack of resources were already impacting patient safety.
He added that he hopes a meeting with HSE management next Tuesday will bring about "robust" proposals to address the concerns of members who he said are "totally frustrated by the intolerable" working conditions.
"What we are looking for is a robust proposal by Government to address this, because the last thing any nurse wants is to go on strike."