Two of Dublin's biggest hospitals, St James's Hospital in the city and and the Adelaide and Meath Hospital in Tallaght, are considering merging.
The boards of both hospitals have given the go-ahead for talks on a possible amalgamation but the discussions are at a very early stage.
However, the fact that staff unions have not been included in the talks up to now has come in for severe criticism.
SIPTU's Dublin health branch secretary, Mr Paul Bell, said worker representatives had been deliberately excluded from the talks. "We were dismayed and angry to learn that the management boards had not seen fit to include the union in the discussions," he said.
He explained there were two representatives of the Tallaght workforce, a nurse and porter, on the hospital board but they were written to in January and told not to attend last month's board meeting. He believed now this was when the issue was discussed. These two staff were finally briefed on the merger plan on Thursday.
Mr Bell said he had written to the hospital's chief executive, Mr Michael Lyons, to complain about their exclusion from the January meeting and for the "covert" way in which the plan was being discussed.
"The lack of communication has raised fears of job losses and loss of services among our members - particularly those who have come through a merger and relocation at Tallaght Hospital," he said. He added that he would also be seeking immediate discussions with the hospital management board and the Minister for Health, Mr Martin, to discuss the development.
A spokesman for the hospitals yesterday confirmed merger talks were under way but stressed they were only at "an exploratory stage".
The hospitals, which between them have more than 1,200 beds, have had close links for some time and it is understood that Tallaght Hospital, which incorporates the National Children's Hospital, has backed St James's in its bid to be the site at which radiotherapy services should be located on the south side of Dublin city when St Luke's is eventually closed.
A separate radiotherapy service is to be located on the north side of Dublin and while a decision on its location was expected this month, it is likely to be much later now given that submissions up to recently had not even been sought from interested hospitals. The competition here is likely to be between Beaumont and the Mater hospitals.