The cost of the new National Children's Hospital (NCH) could top €2 billion, an Oireachtas committee has heard.
The head of the hospital's board warned that unless the contractor changes its behaviour, further delays, and even higher costs, may occur.
The Oireachtas Committee on Health was also told that under 1% of the rooms due to have been completed at this stage have been completed.
The rising costs are the result of claims for an additional €756m in funds made by the contractor, BAM.
The bulk of this - €573m - relates to just 16 claims (out of a total of 2,175).
Those 16 claims are demanding compensation for 2,376 days of delays, which BAM says "is our fault", revealed David Gunning, Chief Officer of the National Pediatric Hospital Development Board (NPHDB).
The board is responsible for overall delivery of the hospital, while BAM is the build-only contractor and is neither the designer nor developer of the project.
The project has crashed through its original completion deadline of August 2022.
Now these latest bills would raise the expected cost of simply building - not commissioning - the hospital to almost €2.2bn.
If approved, they would be added to the original capital budget of €1.43bn, of which €1.35bn has been spent to date.
Mr Gunning also said that the board has submitted a request to Government for further funds.
BAM now says it will not be finished before the middle of next year, with May 2024 being the "substantial completion date", the committee heard.
But Mr Gunning said that BAM's failure to provide an update earlier this month means that no firm completion date can be set.
He warned of "further slippage" if BAM does not change its behaviour, with its output level averaging just two thirds of its target over the past year.
At times, construction activity has fallen to one third of its target.
BAM rejects 'allegations of under-performance'
In a statement following the committee hearing BAM said: "BAM categorically rejects any allegations of under-performance and under-resourcing on the new children's hospital project.
"Any suggestion that BAM is deliberately not committing adequate resources to the project or is in any way slowing down delivery of the hospital is untrue.
"As the Board told the Committee today, the tireless work of BAM, its project staff and supply chain partners has driven the build phase to more than 85% completion to date.
"As referenced during today's committee meeting, BAM confirms it will submit a revised programme of works for the final stage of building the new children’s hospital next week.
"The level of persistent change to the hospital’s design has made the programme submission process complex.
"BAM is obliged under the terms of the contract to raise any variation, including instructions, with a time or cost implication as a 'claim'. This inevitably leads to greater complexity in the claims process and we look forward to the resolution of this in due course."
BAM's failure to deliver on "its contractual obligations" has pushed the NPHDB to "withhold 15% of the payments for works completed" in recent months, Mr Gunning revealed.
At this stage of the project "3,000 rooms should have been completed", he said.
Because of "a large number of snags", he said, "to date, 27 rooms have been deemed complete".
Despite this, he claimed that "construction has advanced significantly" in the past year, with external scaffolding having been removed and the facade complete.
"The 380 in-patient rooms are taking shape", Mr Gunning said.
He also noted that "two expert teams" are currently examining "four ventilation grills in 11 of the 22 operating theatres" after reports that they were substandard.
Elsewhere, Taoiseach Leo Varadkar has said that the hospital will cost "significantly more" than the €1.433 billion cost which was stated in 2018.
Speaking in the Dáil, he said he could not say how much more it will cost, adding that the Government was disputing multiple claims.
He was responding to Sinn Féin's Pearse Doherty who said the Government had "lost all control and credibility".
He asked how much additional money had the hospital's board requested to complete the building.
