The Public Accounts Committee (PAC) has been told there is no legal basis for it to examine the tax evasion claims made by a civil servant in the Department of Jobs, Enterprise and Innovation.
The committee has also been given legal advice this afternoon that it cannot bring Gerry Ryan, who made the claims regarding offshore Ansbacher accounts, before it to give evidence.
A private meeting of the PAC is ongoing, but sources said deputies have also been told they cannot ask Mr Ryan for an additional 700-page document he says supports his claims.
It is also understood the committee has been told Mr Ryan’s initial dossier - which he sent to members last week - is outside its remit.
TDs on the committee are currently discussing their options.
One source said a motion would have to be put before the Dáil to widen the committee’s remit, if it wanted to fully examine the claims.