The Department of Health does not have a working estimate for the final cost of the National Children's Hospital, but has conceded that delays of more than 14 months will add to the final bill.
Fiona Prendergast, the Department's Director of Infrastructure, has told the Oireachtas Health Committee that the final cost is hard to determine.
This is due to "uncertainties that are out there in relation to Covid and in relation to Brexit, and the fact that we still have two years to run on the project".
In response to questions from co-leader of the Social Democrats, Roisin Shortall, Ms Prendergast said the Government originally approved €1.43 billion for the project in December 2018.
"Because it is going to take longer, it is going to cost more. That is the nature of the beast," she said.
It comes as the committee heard the project will be delayed by at least 14 months, with risks of further delays beyond that.
The CEO of the hospital, David Gunning, said this delay is likely to result in an increase in the final cost, but he would not reveal any estimate for that.
The original contracted completion date was August 2022, but Mr Gunning said that "because of the Covid shutdown" the estimated date of completion is December 2023, with an estimated opening date in the second half of 2024.
"That is conditioned by the risks that are currently in the construction sector in terms of resources, availability and supply of necessary materials," he said.
"I think we all recognise we are in a global pandemic and the challenges this provides and all other aspects that impact on the construction project, we are not in a position to provide any definitive dates."
Mr Gunning also warned that this will have cost implications, saying that "any elongation of the programme equates to additional costs" and there have already been cost implications as a result of Covid, additional health and safety measures, as well as ongoing claims from contractors.
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He refused to say what the additional costs are likely to amount to, saying that there are live contracts between the development board and the contractor, BAM.
"Therefore I am not in a position to elaborate further at this time, as it could compromise our ability to negotiate on behalf of the State at a later date," he said.
Mr Gunning added: "There is an extremely strong likelihood that any discussion on costs, however hypothetical, would prejudice enforcement of the existing contract and very likely negatively impact or jeopardise our current engagements with the contractor."
Committee members were strongly critical of the representatives from the hospital and the Department of Health for their failure to give estimated cost updates.
A previous Committee hearing in November heard there were 600 claims outstanding, with an estimated cost of €200m.
When asked by Sinn Féin's David Cullinane how many of these claims have since been settled, Mr Gunning could not be specific, but said it was a "handful".
Mr Cullinane said: "There is a vacuum in my view of accountability and transparency around this project.
"I have to say that it is deeply unsatisfactory. It is eight months since you were last in, and I have to say that the update that we got is far from satisfactory.
"And it just shows that this saga of building this hospital goes from one mess to the next as far as I am concerned."
Taoiseach Micheál Martin told the Dáil there is a "difficult" and "unsatisfactory" relationship between the contractor building the National Children's Hospital and the development board handling the project.
He was responding to Sinn Féin leader Mary Lou McDonald who called for the Taoiseach to give a final cost for the project.
She said there were 900 additional claims but only a handful had been settled. The Taoiseach said he was not in a position to give figures.
