The General Secretary of the Department of Public Expenditure has been criticised for declining to appear before an Oireachtas Committee examining the cost overruns at the National Children’s Hospital.

Robert Watt wrote to the health committee saying he did not think his attendance was required as it is "a matter for the Department of Health".

Speaking on RTÉ’s The Week in Politics, Sinn Féin’s spokesperson on health Louise O’Reilly said Mr Watt should appear at the committee to account for the overspend, tell members at what point the overspend was communicated to him and his department and whether anything was done to curb it.

Minister of State and Chief Whip Sean Kyne said the position of the Secretary General is not sustainable. He said the Department of Public Expenditure quibbles over small amounts of money in other areas.

He said that lessons have not been learned from overruns in the past with PPARS (the health payroll and personnel system) and the Port Tunnel.

Mr Kyne added that the departments of Health and Public Expenditure have to work hand in hand in relation to costs.

The minister was informed of potential increases in cost in August, said Mr Kyne, and the minister informed cabinet just before Christmas when he became aware of the actual figures.

Mr Kyne also pointed out the Luas interlink project came in under time and under budget.

A Government spokesperson has said at present there is no plan for the Comptroller and Auditor General to review expenditure at the new hospital.

The Department of Health has commissioned an independent review by PwC into the escalation of costs and it is expected that will commence shortly.

Fianna Fáil TD Lisa Chambers said "we need to find out what went wrong" so it does not happen again. She said that ultimately, the minister is responsible.

Labour’s Joan Burton said the issue was related to the decision of the Taoiseach to combine the Department of Public Expenditure with the Department of Finance.

Meanwhile, health committee chairman Michael Harty said it was "astounding" that Mr Watt has declined the invitation to attend its meeting on Tuesday.