IRISH Water ignored Government instruction to rely on expertise within Bord Gais during the set-up and instead spent €50m on consultants, a leaked confidential report has revealed.

The organisation – which has been up until now refusing to disclose the details of how the money was spent – said that it will provide a "full and detailed briefing" on set-up costs at the Oireachtas Environment Committee tomorrow.

The confidential report shows that the Government demanded and expected the embattled utility company be set up using Bord Gais' "existing operational capacity" in IT, asset management, customer billing and other key functions.

The previously unpublished 20-page report made no specific mention of the need to rely on external consultants. It also said the decision to hand responsibility for Irish Water to Bord Gais was based on the "central element" that existing expertise in the system be used.

Today Transport Minister Leo Varadkar has said the accountability for expenditure at Irish Water rests with the company's executives.

Mr Varadkar said he believes it is important that Irish Water provides a full breakdown of the €50m spend.

However he refused to back calls for Environment Minister Phil Hogan to appear in front an Oireachtas Committee in order to answer questions about the massive splurge.

Minister Varadkar said the accountability for expenditure lies with the company itself and chief executive John Tierney.

CONFIDENTIAL

"The responsibility really lies with the chair and the CEO and they're the ones who will appear before the committee," he told the Herald.

The confidential document which was leaked over the weekend was drawn up by the Irish Water Consultancy Group, an inter-agency group made up of the Department of the Environment, Bord Gais and local authority unions.

The report from September 2012 was created just six months after the government decided to create Irish Water as a subsidiary of Bord Gáis.

The €50m spending on consultants has gone to pay for advice on asset management services, customer services and other IT functions.

It has emerged that ministers were kept in the dark as to how much Irish Water was spending.

Junior Minister Fergus O'Dowd, who brought the legislation through the Dail and Seanad, said that he first knew of the splurge on consultants was when he heard Irish Water managing director John Tierney speaking on RTE radio.

"I was never aware of the €50m figure until I heard John Tierney announced it on radio," he said.