SIPTU and IMPACT have called on members of their unions who are employed in the health services but are not nurses to work as normal if the nurses' strike goes ahead on Tuesday.
However, both unions have made it clear they will not ask such employees to do any task other than their normal duties.
Mr Kevin Callanan of IMPACT said his union would advise non-nursing members not to carry out tasks normally done by their nursing colleagues.
On RTE radio's News at One he said he was concerned that management was assuming non-nursing staff would "be available to pick up the slack left behind by nurses". He said such an assumption showed an ignorance of the crisis across various sectors of the health service. He wanted to say "loud and clear" that the union's 14,000 non-nursing health workers would be confining themselves solely to the work that they would normally do.
Mr Callanan also asked workers outside the health services to pass the pickets to ensure that deliveries of essential supplies were made during the course of the dispute.
SIPTU's national nursing officer, Mr Oliver McDonagh, said his union was also asking its non-nursing members to go to work as normal, but not do any nursing duties.
While he raised the possibility of other health service employees being asked to join in the strike at a later stage, he said if the unions wished them to do so, they would inform them in writing.
Meanwhile, the South Eastern Health Board expressed concern that the nurses' strike would exacerbate the difficulties caused by an ongoing dispute at Waterford Regional Hospital.
There was some hope of a breakthrough in the dispute last night with the news that management and members of the Technical, Engineering and Electrical Union would meet for conciliation talks this morning.
The strike has severely curtailed services at the hospital, with all non-emergency admissions and services, including most out-patient clinics, cancelled as a result of the round-the-clock picket.
A spokeswoman for the board said last night that cleaning and refuse collection had become a major problem for the hospital. Porters, catering staff and cleaners are involved in the action. "If nurses go out as well as ancillary staff that will lead to major problems," she said.
TEEU members at the hospital went on strike over their claim that supervisors are carrying out the work of plumbers and electricians at the weekend. ATGWU workers have refused to pass their colleagues' pickets, resulting in about 230 workers withdrawing their labour.
Ms Shelia O'Connell of the Irish Patients' Association expressed concern about the prospect of the dispute not being resolved before the nurses' strike. "What is going to happen there next Tuesday? We hear of talk of patients there being moved to other hospitals. Can that be acceptable in a civilised society?"
Commenting on the broader dispute she said it was "totally unacceptable that next Tuesday there's going to be a situation of absolute chaos in our hospitals".
