The Psychiatric Nurses' Association (PNA) has said the nurses' dispute is a "slow burner" and vowed nurses will continue their protest until the Government is willing to talk to it.
Seamus Murphy, spokesman for the PNA, told ireland.com: "The nurses are prepared to see this out. We're in this for the long haul. Our aim is to get management to come to the table."
Three weeks of talks with the National Implementation Body broke down at the end of March, when the Government and nurses' unions failed to reach agreement over nurses' calls for increased pay and improved work conditions.
Mr Murphy said the Government had promised an "open and creative agenda" for negotiations but failed to deliver it.
He said the PNA and Irish Nurses' Organisation (INO) were willing to be flexible in talks over modernisation plans and would discuss changes to work practices, roster changes and new nursing grades in return for their pay and conditions requests.
However, Mr Murphy said the Government's insistence that the benchmarking process was the only way forward was not appropriate.
"We've been told for the last two years that the only game in town is benchmarking," he said. "But it is a game that is not capable of resolving the issues."
Earlier today the Health Service Executive (HSE) said its dispute with the nurses was deadlocked and appealed to the INO to talk to it.
Brendan Mulligan, a spokesman for HSE Employers Agency, also told ireland.comthat comments made by INO general secretary Liam Doran on RTÉ radio this morning were "very unhelpful".
Speaking on Morning Ireland, Mr Doran insisted that HSE employers must name a date for the introduction of a 35 hour week and assured listeners that work-to-rule action would continue until a 10.5 per cent pay increase was secured for its 40,000 members.
Mr Mulligan insisted the HSE had agreed to "engage" with the INO and the PNA, but he said it was necessary for each hospital to carry out an assessment of its own requirements "to see what is possible and what is not possible" before a risk assessment of patient safety and costs could begin.
"We cannot give a date [for the introduction of a 35 hour week] until we know what's involved," he said. "Liam will have to stop setting out preconditions . . . we can't give a date until he comes to talk to us."
The union began industrial action on Monday last week, with work-to-rule and then work stoppages on Wednesday in St Vincent's Hospital in Dublin and in South Tipperary General Hospital, Clonmel, and South Tipperary Mental Health Services.
Further one-hour stoppages are expected tomorrow in four hospitals in Dublin and Roscommon. Nurses are set to protest from 11am until noon outside Dublin's Beaumont Hospital; St Ita's Psychiatric Service and St Joseph's Intellectual Disability Service, Portrane; Roscommon General Hospital; and Roscommon Mental Health Services.
In a statement today, the HSE's north east area said contingency plans have been agreed for St. Ita's ahead of the stoppage tomorrow.
"St. Ita's Mental Health Service and St. Joseph's Intellectual Disability Service hopes to be in a position to provide services, with minimum disruption to clients during the work stoppage," the statement said.
"There will be some restrictions on the Mental Health & Intellectual Disability Day Services, Outreach Services and out-patient clinics. The majority of appointments have been rescheduled for that afternoon and clients notified accordingly.
"The management wishes to apologise in advance for any inconvenience and to thank the public for their co-operation."
In a statement, Beaumont Hospital said it had been working with the INO and its representatives to ensure there is no major disruption of services arising from the stoppages tomorrow.
"Full emergency cover has been guaranteed and all services will run as normal, with two exceptions. Six out of 42 scheduled endoscopy procedures have been rescheduled. These will take place within the next week. Twenty out of 70 scheduled appointments have been rescheduled in one surgical outpatients clinic and these will take place over the next two weeks," the statement added.
"Apart from these, the hospital hopes to provide services as normal. Management wishes to apologise in advance for any delays which may result from the industrial action and to thank the public for their co-operation. It also stresses that unless notified to the contrary, patients with appointments at Beaumont Hospital tomorrow should attend at the appointed time."
The hospital has asked that members of the public keep phone enquiries regarding the welfare of in-patients to a minimum because phones are not being answered by nurses on wards.