The Western Health Board has said it is still hopeful of a "positive outcome" to talks on overtime pay with general and psychiatric nurses working in the region. This follows SIPTU's decision to ballot on strike action.
The dispute between the health board and SIPTU has already resulted in a work-to-rule in Co Mayo psychiatric services. SIPTU's secretary in Galway, Mr Michael Kilcoyne, said this action may be escalated if there is no agreement.
The union is accusing the board of failing to implement agreements which had been made at national level on pay rates for overtime.
According to Mr Kilcoyne, some nurses have not been paid for overtime due for five months. He also expressed concerns about health and safety in many institutions in the board's region.
The ballot result is expected next week.