Minister for Health Simon Harris has said that he always approached his role in a spirit of cooperation with opposition parties when it came to tackling big issues.

Speaking as he arrived at Cabinet this morning, Mr Harris said he was not sure when the planned motion of no confidence in him would be tabled by Sinn Féin, but he was looking forward to getting on with the job at hand.

His comments came as ministers prepared to consider proposals to find €100m in this year's capital budget to cover the cost overruns on the National Children's Hospital.

He said: "Even though it’s costing more, and that’s frustrating, we still must actually build this hospital.

"To do anything else would have been a scandal and would have let the children of this country down. They have waited far too long for this."

Mr Harris apologised to the Dáil this afternoon over the answers he gave to the house last year about the projected cost of the hospital.

Back then, the minister had seen documents suggesting the price was escalating, but he gave no hint of that in his answers.

This morning, Mr Harris said the overrun at the hospital needed to be viewed in the context of the Government's overall capital budget.

He said the increase in capital spending would be about €1.1 billion this year, but that some 'headroom' needed to be found.

Mr Harris said the issue of whether or not he retained the confidence of the Taoiseach and other ministers did not arise.

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The Taoiseach said the Government had underestimated the cost of the National Children's Hospital and must take responsibility for that.

Leo 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.

Mr Varadkar told the Dáil that the Government accepts responsibility for the escalating costs at the Children's Hospital, and that lessons have to be learned.

Leo Varakdar was responding to Fianna Fáil leader Micheál Martin during Leader's Questions this afternoon.

Mr Martin said there has still been no explanation as to why the Minister for Finance was not informed of the danger of the escalating costs.

"Are we seriously to believe that the secretary Generals of Finance and Health had no discussions about this between August and November last year, or indeed that the two ministers didn't, because if that is the case, then that raises fundamental issues in terms of the governance and management of budgetary process itself," he said. 

Fianna Fáil's Barry Cowen has said he hopes to be in a position to accept Mr Harris' apology later.

The Minister was responding to a question from Mr Cowen last September, who asked him about the cost of the project. 

However, the Sinn Féin leader has said that sorry will not be sufficient in light of the €450m increase in spending on the project.

Mary Lou McDonald urged people in Fianna Fáil to break ranks with the party's leadership and to support the Sinn Féin no-confidence motion in the Minister for Health next week.

Speaking in the Dáil this afternoon, Ms McDonald said: "Fianna Fáil might be prepared to sit on its hands. We won't."

She said the Taoiseach should release Simon Harris of his duties.

Additional reporting: Micheál Lehane