The HSE has admitted that a spend of more than €17m on agency staff at UHG and Merlin Park last year is "unacceptable".
The issue was raised at a meeting of the HSE Health Forum West last night by Councillor Shane Forde.
He found the figures incredulous and said they surely could not be sustainable.
Management admitted the figure is not acceptable, and said it's due to a range of factors, including unplanned leave and UHG being under extreme pressure since October.
Fine Gael Councillor Forde says it's good they've acknowledged the problem - but now they have to fix it.