The Public Accounts Committee is to invite the board of the new children's hospital to appear before it to explain the escalating costs involved in the project.
Fianna Fáil TD Bobby Aylward said the projected costs had escalated to €1.2bn before a sod had been turned.
Previous estimates had put the cost at €650m before the building is equipped.
Committee Chairperson Sean Fleming said the matter had been raised by Independent TD Mattie McGrath and members agreed to write to the board to invite them to appear before the committee.
Comptroller and Auditor General Seamus McCarthy told committee members that it should be clear where cost escalations occur and why.
However, he also told the committee that the audit function was retrospective and his office could not get involved in decision-making.