SIPTU is demanding an urgent meeting with the operators of two nursing homes over the alleged non-payment of staff wages for two weeks.
Cloverland Healthcare runs the homes in Athy, Co Kildare and Shinrone, Co Offaly.
The union says up to 72 staff have been left without wages, and cheques issued to the workforce on February 9 were refused by the bank.
Cloverland Healthcare has blamed the matter on the late issuing of registration certificates by the Health Information and Quality Authority (HIQA).
However SIPTU said that while HIQA visited the Kildare home today, it was only to check on patient care, not to discuss any issues of certification.