The Irish Nurses and Midwives Organisation has pulled out of talks with the HSE West at the Labour Relations Commission.
The negotiations centre on proposed cutbacks to deal with a €90m deficit.
Up to €65m worth of cuts will be imposed between now and the end of the year in the west, with 200 job losses expected among temporary staff.
But the INMO has said it is no longer taking part in the LRC talks pending a full Labour Court hearing.
The organisation said it is "because 376 pre-registration nurses are also being released without the regulated number of replacement qualified nurses".