The Dáil has been told that there are significant legal problems in seeking the return of allowances and bonuses which were given to some university heads without government sanction.
Junior Education Minister Sean Haughey was responding to revelations that the University of Limerick paid a president's salary to three people at the same time in 2007 and 2008.
Fine Gael's Fergus O'Dowd said the university was "getting away with murder and the money should be paid back".
But Minister Haughey said there are legal problems with recovering the funds.
"Under the current legislation my department is limited in its options in respect of imposition of penalties to deal with breaches," Minister Haughey told the house today.
"While the extra payments were ceased in April 2009, in most cases this did not have the retrospective effect.
"In view of possible contractual entitlements there are significant legal obstacles to recovering unauthorised payments from individuals."