The spend on the National Children's Hospital (NCH) could hit €2bn as senior health officials could offer no guarantees to the Dáil's spending watchdog that spiralling costs have been halted.
The National Paediatric Hospital Development Board (NPHDB), the boss of the Department of Health and HSE representatives faced intense questioning as they appeared at the Public Accounts Committee (PAC) to account for the overspend.
It comes after it was revealed construction costs of the hospital soared from €983m to more than €1.4bn. With another €300m due to be spent fitting out the hospital with ICT equipment, the total cost is expected to be more than €1.7bn.
Labour TD Alan Kelly challenged department secretary general Jim Breslin on whether he could guarantee the project will come in under €2bn.
Mr Breslin said his department was studying if there were likely to be extra costs but it was not yet completed. He said the only variation on the €1.433bn guaranteed maximum price of construction costs would be items not covered by the contract.
Mr Kelly said he noted Mr Breslin didn't offer a guarantee the project will come in under €2bn and an exercise is being conducted "to see how much cost creep there will be".
He said it was "mind-boggling" the previous €989m estimated costs couldn't be guaranteed and now "we can't guarantee to the taxpayer that this will come in under €2bn".
Mr Breslin said the department would be "fully open" on items outside the contract and added it would obviously be an estimate to "try and predict where construction inflation goes over the next four-year period". He insisted it was an achievement to have a guarantee on the maximum price.
He also said the Government would also use non-exchequer funding to limit the taxpayers' costs, earlier saying that it was hoped €168m would come from philanthropic sources.
Mr Kelly predicted the costs would hit €2bn and claimed public confidence in the State delivering large projects at the estimated target cost was gone.
Fianna Fáil TD Shane Cassells questioned if Health Minister Simon Harris misled the Dáil last September in response to a question on the NCH budget from party colleague Barry Cowen.
He said Mr Cowen was told the hospital budget was coming in on target but it was now known Mr Harris was told at the end of August the budget was "already out of control".
Mr Breslin said the costs incurred at the point the question was asked were "on profile". There had been concern about "emerging trends" but the scale of the cost increases had not been known until November.
Later, Fine Gael TD Kate O'Connell raised concern over the make-up of the NPHDB and its reappointment last year. She questioned why it did not include a specialist nurse or someone who worked in Crumlin hospital.
"The make-up of the board seems like it would be a recipe for disaster," she said. Mr Breslin replied that the 2013 decision about the formulation of the board "was around the skills required to deliver the biggest construction project that would be undertaken in the public sector".
A HSE official said no decisions have been made on what other projects may be halted or postponed due to the cost overrun.
The department had to find €50m to cover increased costs of the project this year and another €50m found elsewhere from the Exchequer.
NPHDB project director John Pollock told the PAC the board was "deeply disappointed" at the increase in costs but the focus now was on delivering a hospital of "outstanding quality" for the care of sick children.