The bitter row between the airport regulator, Mr Bill Prasifka, and Ryanair chief executive Mr Michael O'Leary has escalated in fresh correspondence between the parties.
In a letter this week from Mr Prasifka, the Ryanair chief is accused of being "intemperate, ill informed and unconstructive" in his views on airport charges and the powers available to Mr Prasifka's office.
Mr Prasifka's letter was posted on his website last night and a copy has been sent to the secretary-general of the Department of Transport, Mr Julie O'Neill.
Mr O'Leary has stated previously that Mr Prasifka should resign because he has not done enough to reduce the costs of air access to Ireland. He has also suggested the accounts of the airports regulator be examined by the comptroller and auditor general.
Responding, Mr Prasifka writes: "The substance and tone of your correspondence, however, is intemperate, ill informed and unconstructive. Your consistent refusal to engage this office in formal consultation at the appropriate times and opportunities is particularly unhelpful."
Mr O'Leary has characterised the recent review of aviation terminal service charges as "laughable" and "gobbeldeygook", but Mr Prasifka rejects this.
"The Commission's proposals arise out of a determination it made in 2002 following statutory consultation. Ryanair refused to participate in the consultation leading up to the 2002 determination. Unfortunately, it would appear now that Ryanair is refusing to make a meaningful submission on the proposed review."
Mr Prasifka claims Ryanair has refused to make submissions on airport charges, but still insists on complaining about them. He also points out he has no role regarding Dublin Airport taxi fees. Mr Prasifka also points out that his accounts are already audited by the comptroller and auditor general.
"Ryanair's complete failure to meaningfully engage the commission in its statutory duties, or to even attempt to understand the statutory basis of the commission, has had the effect of denying the commission the opportunity of addressing Ryanair's concerns in the only way it is able to - in a formal statutory consultation process," writes Mr Prasifka.
Earlier this month Ryanair claimed the regulator had failed to control the inefficiency and excessive costs levied by Aer Rianta at Dublin Airport.
Mr O'Leary called on Mr Prasifka to resign. "This regulator has failed the Irish aviation industry. He should resign or be replaced. Better still, the Government and the Minister for Transport should proceed with their plans to break up the airport monopoly and introduce competition in the form of a second terminal, which will do away with this ineffective and inefficient regulator."
