The Dublin Airport Authority (DAA) said today it was disappointed by the aviation regulator's decision not to raise airport charges.
The DAA said the regulator's "complex proposals" provided insufficient clarity on the investment needed at Dublin Airport.
Earlier the Commissioner for Aviation Regulation (CAR) Cathal Guiomard announced he believed it would still be possible to maintain the work being done at the airport at the current rate of €6.34 per passenger.
The DAA had said that a rise in charges was necessary to fund the new second terminal and to carry out "much needed infrastructure investments to boost capacity" at Dublin airport.
CAR decided to review the levels of charges to consider the DAA's capital investment plan, which had not been available to him when the current rate was decided upon.
Ryanair condemned today's decision, claiming it was failing to put passengers ahead of the DAA's profits.
The carrier said the regulator is leaving the existing charges unchanged, so they will continue to increase with inflation, despite "the third world facilities being provided by the DAA monopoly".
The airline's chief executive Michael O'Leary said: "This is another rubber stamping exercise by another Government-appointed regulator who has failed to control a semi-state monopoly."
Mr O'Leary said: "The DAA plans to waste €800 million building a facility which should cost just €200 million and which will result in significantly higher passenger charges in years to come."
"This is just another case of the Aviation Regulator failing Irish consumers," he added.
Announcing his decision, Mr Guiomard said: "We have concluded that Dublin airport's ability to obtain the funds to allow its investment plans to proceed will not be compromised by leaving the price cap at its current level of €6.34 per passenger,"
He said the DAA was proposing to build a larger terminal than would seem to be required by user demand, suggesting that it might be wiser to build a smaller terminal that could be extended at a later date if necessary.
"It is not the role of a price regulator to dictate to a regulated firm the location, scale or design of a project," he said.