The Dáil's Public Accounts Committee has been told it cannot compel two former Rehab CEOs to attend a public hearing.
The committee has been told that it cannot be given the power to compel witnesses who do not work for an agency under the direct supervision of the State spending watchdog.
TDs had wanted to question Angela Kerins and Frank Flannery over their role in using public funds to support the wages of highly-paid executives.
However, the PAC has been told it can compel three other individuals to appear in relation to a separate inquiry about the use of a HSE training fund.