The Taoiseach has denied that the Government presented an inaccurate revised volume of expenditure to the Dáil last December.
He was responding to a question from Labour leader Brendan Howlin about the cost of the overrun of the new National Children's Hospital.
Leo Varadkar said the Budget was agreed by the Government in October and that the Government did not know the full cost of the overrun on the children's hospital until November.
He said the Government did not decide on the relocation of funding until the Cabinet meeting this week.
Mr Varadkar also said every year money is transferred from one capital project to another and from one department to another.
He said the amount of money being invested in public infrastructure this year has not changed and is €7.3 billion which is around €140 million a week.
The Taoiseach said roughly a weeks' spending would have to reallocated within the additional capital spending.
He said the Government accepted responsibility in the under estimate in relation to the NCH and they would deal with it and build the project, which would be open between 2022 and 2023.
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Earlier, Minister for Finance and Public Expenditure and Reform Paschal Donohoe said he accepts his role in what went wrong in relation to the cost overruns at the national children's hospital.
"I accept what went wrong here and my role in it. We have to acknowledge was has gone wrong in this Capital Programme," he said.
He also backed under fire Minister for Health Simon Harris.
Speaking on RTÉ's Morning Ireland Minister Donohoe said: "Minister Harris has performed his role with immense competence and skill.
"We had a very big difficulty here that I take responsibility for, something that went very, very wrong here.
"I have no doubt Simon was under full appreciation of the scale of the problem and how it would affect the hospital.
"Of course, we should have done things differently and we will learn for the future."
"When my department became aware of costs we acted promptly in conjunction with Mr Harris. Things went wrong we should have handled this better, and have learned for the future.
"I fully accept my responsibility in this and so does the Health Minister."
He said there are two things that can be learned for the future, one being that the two-stage procurement process will be used less, and they will be used by exception in the future.
He said the Government will also then ensure we better "price in risk" in terms of their delivery.
Mr Donohoe said clarity cannot be given on whether costs will rise further, however he feels it is more important to revisit where they are now on the project.
Mr Harris will return to the Dáil chamber at 6pm to face questions from Opposition TDs about when he learned about the cost overruns, what he did with the information and why did he did not raise the revelations at Cabinet.
Sinn Féin has said it still intends to table a motion of no-confidence in Mr Harris as soon as possible.
In September last year, Mr Harris said in the Dáil that he was not in a position to give commercially sensitive figures.
But yesterday he said that he should have answered the question more fully as it was never his intention to mislead the Dáil.
"I should have added further detail to inform that a process was ongoing to finalise costs and that updated costs would be known when that process concluded. I apologise for not doing this," the minister said.
He added that he would account for his actions and decisions, and would ensure others are held to account for theirs.
"We will not be found wanting when it comes to acting against any entity or any company if errors were made," he said.
The Taoiseach said the Government had underestimated the cost of the National Children's Hospital and must take responsibility for that.
Mr Varadkar said construction inflation was one of the reasons for this but it was not the only one.
He said the Government accepts too that lessons will have to be learned.
Additional reporting Paul Cunningham