Taoiseach Enda Kenny has said that Rehab should reveal the salaries of some of its senior managers.
Mr Kenny says all agencies who receive state funding should be transparent about the ways in which that money is used.
The Fine Gael Ard Fheis has adopted a motion which would make it mandatory for charities like Rehab to disclose the salaries of their chief executives if they receive state funding.
But the Taoiseach refused to be drawn on whether Frank Flannery - a senior Fine Gael advisor - should have attended last Thursday's meeting of the Public Accounts Committee (PAC).
Mr Flannery is one of the directors responsible for setting the pay of senior managers at Rehab - but didn't attend the hearing.
"As I say he (Mr Flannery) is a member of the board," Mr Kenny told reporters.
"He's not an employee of Rehab - it's a matter for the board.
"I said very clearly that… where public monies are involved, people should be forthcoming about evidence of salaries and so on."