The Irish Kidney Association has said it is "hugely disappointed" that the pancreatic transplant programme has yet to begin at St Vincent's Hospital in Dublin.
No pancreas transplants have taken place in Ireland since the retirement of surgeon David Hickey at the end of 2014.
The programme was transferred from Beaumont Hospital to St Vincent's and was due to begin its work last September.
However, RTÉ News understands that issues have arisen surrounding nursing staffing levels and this has now been referred to the Workplace Relations Commission.
Two consultants and a transplant fellow have been appointed to the programme as well as two transplant co-ordinators.
A transplant nursing clinical facilitator has also been appointed.
In a statement, the Department of Health said it is anxious this issue is resolved as a matter of urgency and that the interests of patients are put first.
In July 2015, the then health minister Leo Varadkar outlined what was happening with the programme in the Seanad.
He pointed out that following the retirement of Dr Hickey and "given the limited number of surgeons who specialise in transplantation, the filling of such vacancies poses a challenge".
The waiting list for transplants has been suspended.
St Vincent's said it has received 25 referrals - 12 women and 13 men - for kidney and pancreas transplants.
The hospital said there is continuous contact with patients and all have undergone pre-operative surgical and anaesthetic evaluations and assessment.
It said that all the necessary arrangements for the operation of the National Pancreatic Transplant Programme are now in place.
However, it said agreement has yet to be reached with the Irish Nurses and Midwives Organisation on rostering arrangements for nurses in theatre for transplant services.
