The Taoiseach has said he cannot rule out the cost of the new National Children's Hospital rising again.
Leo Varadkar confirmed the hospital, which will be located on the St James's Hospital campus in Dublin, will now cost €1.4 billion - more than double the original price tag.
The cost of the project has risen by €400 million in the last six weeks alone, with around three quarters of that down to a rise in construction costs.
The Taoiseach said: "There will be further investigations as to how these costs escalated by so much since April last year".
He noted that officials with the National Paediatric Hospital Development Board will be available to brief Oireachtas committees about the project - including the reasons behind the escalating costs.
When asked it the price could rise further, the Taoiseach acknowledged: "It is possible".
Aerial view of the planned hospital
Mr Varadkar said the hospital may turn out to be one most of the expensive in the world, but insisted it will also be one of the best.
Fianna Fáil TD Stephen Donnelly has claimed you 'couldn't make up the level of incompetence' involved in the project.
Taoiseach tells @MichealMartinTD that costs of Children’s Hospital has risen €450m. Due to building costs, design, etc. So not a single additional service or bed or doctor...for €450m. You couldn’t make up this level of incompetence.
— Stephen Donnelly (@DonnellyStephen) December 18, 2018
Meanwhile, Fianna Fáil leader Micheál Martin said the increasing costs are unbelievable and "beyond comprehension".
The main campus of the new children's hospital is expected to open in 2022.
Reporting by Sean Defoe and Stephen McNeice