The SIPTU trade union has warned that industrial action may be imminent again at University College Hospital in Galway and other Western Health Board institutions, if management fails to honour an agreement made with nurses last November.
SIPTU, which claims to represent 3,000 Western Health Board workers, is to ballot its 1,500 nurses in the region over the next few days to decide if industrial action is to be taken.
Mr Michael Kilcoyne, the union's Galway branch secretary, said the ballot was being taken because patients were not getting the care they needed.
"We are taking a ballot to decide whether industrial action will be taken if we fail to resolve the issues which we have raised with the health board management," he said. "It may take the course of non-co-operation or work-to-rule. Our members have already taken work-to-rule action in Mayo.
"Patients deserve and expect a high level of care, but they do not get it because the wards are understaffed."
Responding to claims that some nurses had worked for nine years for the health board without being offered permanent positions, a spokesman said dates were being set for interviews to appoint full-time members of staff.
Mr Kilcoyne said nothing had changed since the controversy last November over threatened ward closures at University College Hospital.