The Health Service Executive (HSE) and the Department of Health are to seek outside consultants to advise on the size and scope of the planned new national children's hospital.
The consultants appointed will be asked to draw up a brief for the new hospital including the number of beds and theatres.
They will also be asked to advise on clinical and non-clinical services to be based at the new hospital and to make recommendations on the configuration of services including provision for the development of a maternity unit on the site.
Yesterday the Archbishop of Dublin, Dr Diarmuid Martin, said he hoped the plan for a new children's hospital would be moved forward with "single-mindedness . . . putting aside questions of personal and institutional interest, to attain what is best for the children of Ireland".
Speaking at a Mass in Dublin's Pro-Cathedral to mark the 50th anniversary of Our Lady's Hospital for Sick Children Crumlin, he also said: "I have no idea what the situation will be in 50 years time and what my successor might say at the centenary. What I do know is that the next 50 years will bear all the marks of the experience of the generosity and personal commitment which made Crumlin children's hospital what it is. If that commitment and generosity is in any way soured or frustrated by not fully and coherently availing of the current opportunity then we will have lost something quite precious for society."
Under the HSE's plan the three children's hospitals in Dublin will be merged into one. It will be located on the site of the Mater hospital.
But the leaders of the main Protestant churches in the State have urged the Government to consider basing the hospital across two sites, which would include the site of Tallaght hospital.
Meanwhile, the outside consultants who will be engaged to advise on the size and scope of the new hospital will be asked to bear in mind the findings of a review of maternity services commissioned some time ago by the HSE. The consultants will also be asked to take account of international trends and new technology and innovations in their report.
It is understood that the consultants will be expected to produce their report by next spring.
This will be given to a new development board for the hospital, which will be established by Minister for Health Mary Harney in the new year.
The consultants' report will be used as the basis for the full design brief for the hospital which will be drawn up subsequently. Last February another consultants' report commissioned by the HSE recommended that a 380-bed centralised children's hospital be established in Dublin.
This would replace existing in-patient facilities for children in Our Lady's hospital, Crumlin, Tallaght hospital and Temple Street hospital.
Last June the Government decided that the new national children's hospital should be established on the campus of the Mater hospital. In addition the HSE is committed to developing two or three new A&E facilities or urgent care centres at strategic locations to support the new centralised hospital.
