Update 6.20pm: The Dublin Airport Authority is labelling An Taisce's claims that its planning application is going to increase congestion on the M50 as 'rather bizzare'.
The DAA says it will not result in a single extra car parking space.
An Taisce is opposing its application to continue to keep almost 11,000 long-term car park spaces.
DAA Chief Communications Officer Paul O'Kane says they only want to make them permanent and they do not cause gridlock.
He said: "What this application is seeking to do is change the existing planning status of this long-term car park.
"It has currently got a temporary planning permission and we want to change that to permanent.
"Our busiest time of the day is between 6am and 7am, that creates demand on the M50 at about 5am which is well in advance of the morning rush hour."
Earlier: Call for major reduction of car parking at Dublin Airport to reduce M50 congestion
There is a call for a major reduction of car parking at Dublin Airport.
An Taisce also wants to see higher parking charges to fund public transport, as it says parking levels are causing gridlock on the M50.
An Taisce is against the DAA's application to continue to have almost 11,000 long-term car park spaces.
An Taisce's Ian Lumley says a special bus service needs to be provided to the Airport to tackle congestion.
He said: "The traffic to the airport is getting more and more entangled and growing congestion on the M50 so it makes no sense for people having to leave earlier and earlier to try and get to a flight on time if they are going to be blocked in traffic rather than get express bus services."
- Digital Desk