The Public Accounts Committee has sought further information from Rehab following legal advice heard in private this morning.
Rehab representatives, including CEO Angela Kerins, appeared before the committee last week.
PAC Chairman John McGuinness said he thought he had agreement from the group to release information on pay scales above grade eight within days, but he said the information had not been received to date.
He said the committee would remind Rehab of this.
Mr McGuinness said the committee's work on Rehab had not concluded.
Sinn Féin TD Mary Lou McDonald said the committee should reissue an invitation to chair Frank Flannery and the remuneration committee to appear before them.
She said the timing would have to be such that the committee should receive the information sought first before the appearance.
She asked that the committee also seek further information on the use of helicopters and jets by the CEO and potentially other board members.
Fine Gael TD Simon Harris said it was offensive to the committee that the delegation sought was not provided.
He said it was normal for the chair of the board to attend with the CEO.
Mr McGuinness said it may be unfair to Mr Flannery to say he was not in attendance, saying he may not have been invited.