The Government is under pressure to widen the scope of an investigation into allegations about a conflict of interest for a senior member of An Bord Pleanála (ABP).
It has been alleged that deputy chair of the board, Paul Hyde, did not declare a conflict of interest he had when making a planning decision on a proposed development in Blackpool on the northside of Cork city.
Further reports have suggested that Mr Hyde also had a conflict of interest in a number of planning decisions relating to an engineering firm which had done work on proposed developments that had come before the board.
Mr Hyde has temporarily stepped aside while an investigation is being conducted by senior counsel Remy Farrell.
Social Democrats TD Cian O'Callaghan told the Dáil that the terms of reference for the investigation were published by the Government last week but they "already appear to be out of date" as further allegations have come to light.
He said the scope of the review must now be expanded "given the centrality of An Bord Pleanála to the planning process and the absolute necessity that it retains the confidence of the public".
Mr O'Callaghan added: "The terms of reference for Mr Farrell's inquiry allow for the exercise of a certain level of discretion in respect of the scope of his investigation but this discretion appears to be quite limited. The terms clearly debar the investigation of anyone other than Mr Hyde."
Tánaiste Leo Varadkar said the "serious allegations" made need to be taken seriously and properly investigated, but "people are entitled to due process as well".
He said Mr Farrell has been given six months to compile and any widening of his work would be a matter for Housing Minister Darragh O'Brien to consider.
"Obviously, he will need to see whether the additional allegations have substance and, on foot of that, will need to make a decision as to whether the terms of reference need to be changed or the investigation widened," Mr Varadkar told the Dáil.