Ryanair boss Michael O'Leary has called the transport minister "incompetent" and "an idiot" and hit out at the Green Party over its opposition to raising a cap on passenger numbers at Dublin Airport.
The airport's operator, daa, is seeking permission to raise the cap on passengers from 32m to 40m a year over the next two years, a move which drew an objection from junior minister Joe O'Brien.
The Green Party TD for Dublin Fingal's objection was one of 380 submissions made before the deadline on Monday.
Mr O'Brien's submission says that the move "will significantly increase noise exposure from aircraft to residents of north county Dublin and cause a significant increase in greenhouse gas emissions".
"During a climate emergency, I believe it is contrary to our national and international commitments to expand airport passenger numbers by 25%."
Mr O'Leary told RTÉ radio that Transport Minister Eamon Ryan is "incompetent" and "does not want to touch Dublin Airport".
He said the cap remaining in place would mean higher air fares in the future and that Mr Ryan had a "block" on expansion of the airport.
"We have this absolute joke of a situation where we've just opened a second runway which creates more capacity, but now none of the airlines can grow and from a selfish point of view, this is great for Ryanair's business.
"I mean, if we can't grow at Dublin Airport, it's inevitable that air fares will rise for the next couple of years... while we have a transport minister who sits there and does nothing."
Mr O'Leary said the "Greens and the idiots on the left" wrongly want to tax aviation companies and said that the idea of using Shannon or Cork more instead of increasing the Dublin cap is "the kind of stupidity only a Green minister would give you".
"50% of the passengers on our flights are inbound passengers.
"If they wanted to go to Cork, we'd fly them to Cork.
"If they wanted to go to Knock, we'd fly them to Knock.
"The vast majority of those passengers, the vast majority of that hotel accommodation is in Dublin — they want to come to Dublin."
The Ryanair CEO denied there is "intense congestion" around the capital's airport but said there had to be an expansion of the boarding gates in the terminals.
Asked about the issue at the launch of the Wayfinding Centre in Glasnevin in Dublin, Mr Ryan said he could not interfere in the planning system.
He said that Mr O'Brien is entitled to his view as both a person and a representative for the area.
"I'm in a different position as the minister of transport, there are additional legal considerations... Fingal County Council and the other authorities have to assess the planning permission and as minister of transport I have to be careful not to intervene in what is a legal process."
A spokesperson for Mr Ryan later declined to respond to Mr O'Leary.
At the same event, Public Expenditure Minister Paschal Donohoe said he is "supportive of any project in any airport that can make a difference to access and transport into our country".