HSE support workers at University Hospital Waterford are to be balloted for industrial action.
Trade union Unite says it is because of an HSE application to the High Court for an injunction against employees from other departments who have refused to pass picket lines.
Over 125 Unite members, working for cleaning services provider Momentum, have been on strike since Tuesday 25 February.
The dispute centres on union claims that conditions of employment had been changed since the company took over the provision of cleaning services at the hospital.
Unite represents around 350 support staff including porters, healthcare assistants and catering staff.
Commenting, Unite Regional Officer Tony Kelly said:
"Rather than instructing Momentum to abide by accepted industrial relations procedures and desist from imposing unilateral changes to our members' conditions, the HSE decided to aggravate the situation by seeking an injunction against Unite members working for the HSE who refused to pass pickets placed by their Momentum colleagues.
"Following this provocation, a general meeting of Unite members working for the HSE decided to ballot for industrial action unless the HSE withdraw its application to the High Court and immediately instructs Momentum to reverse the unilateral changes to our members' working conditions.
"The HSE now has a choice. They can withdraw their application for an injunction and instead instruct Momentum to abide by normal industrial relations procedures - or they can continue adding fuel to the flames and provoke industrial action by all support staff in University Hospital Waterford.
"Resolution of this dispute is in the HSE's hands", Tony Kelly concluded.
