The Dublin Airport Authority (DAA) has said Ryanair is using inaccurate and misleading information to delay the building of a second terminal at Dublin airport.
The airline is one of seven parties who have lodged objections with An Bord Pleanala against the development of T2 on the basis that it is too expensive.
Ryanair claims construction of the new terminal will cost around €800 million.
But the DAA criticised Ryanair for what it described as its "latest batch of inaccurate information", insisting the only budgeted cost published by the authority for the 75,000 square metre terminal is €395million.
"This price has been independently verified as in line with the cost of equivalent facilities at other large European airports," the DAA said.
The DAA admitted that passengers, rather than airlines, would ultimately pay for the building of the new infrastructure through a small proportion of their airline fares, but maintained that contrary to what Ryanair had suggested, airport charges at Dublin airport would not double to pay for T2.
"The Commission for Aviation Regulation has set Dublin airport's current maximum airport charge per passenger at €6.34, " a DAA statement said.
"The DAA has sought an increase of just over €1 in the average airport charge over the next three years to pay for T2 and other new facilities, costing a total of €1.2bn. This requested average charge of €7.50 is significantly lower than the cost of many standard airline services. This charge would still leave Dublin airport with the lowest charges of any major European airport."
The DAA also refuted suggestions that the delivery of the new terminal would limit annual passenger volumes through the capital's airport to 30 million people.
"The planning permission granted to the DAA for Dublin airport states that planning must begin for delivery of a third terminal when passenger numbers reach 30million. T2 will deliver comfortable capacity for up to 35million passengers at Dublin airport, thus providing up to 10 years of headroom for growth after 2009," the DAA said.
Other appellants to An Bord Pleanala include Portmarnock community association, which is understood to have objected on environmental grounds and An Taisce, the national heritage agency, which is believed to have objected over the issue of air pollution.
Third party appeals were lodged by the groups on November 20th last year and a revision date for the case hearing has now been set for August 3rd this year.
The DAA, which secured planning permission to build the new terminal on October 25th last year, says it will provide "urgently required" space, comfort and choice to the millions of passengers passing through the airport every year.
However, it too has lodged a first party appeal with An Bord Pleanala in relation to some of the provisions set down in the terms of its planning conditions.