Minister for Transport Paschal Donohoe has said if air traffic at Dublin Airport continues to grow at the same pace as it has so far this year then a new runway will be needed.
The minister was speaking at the announcement of expansion plans by Ryanair. Over 21 million passengers used Dublin Airport last year, with growth of 15% forecast for this year.
Plans for a new runway were shelved in 2010 after the downturn badly affected air travel.
Dublin Airport Authority says it currently examining the various options regarding the delivery of a second parallel runway at Dublin Airport, but have not yet made a final decision in relation to this issue.
A spokesperson for daa said "a second runway remains a central element of Dublin Airport's long-term plans."
Ryanair to add new Dublin-Amsterdam route
Meanwhile, Ryanair has said its new "friendly" image is working out, and it is planning to roll out more customer friendly features in the coming year.
As well as adding a new Amsterdam-Dublin to its Summer 2016 schedule from 27 October, the airline is updating its image, with "less yellow" interiors, "more stylish" uniforms and more leg room.
New digital features from the airline will include a personalised website and a "hold the fare" feature.
Ryanair carried 30 million passengers over the 12-week summer period, more than both KLM and Air France carried in the entire year, according to Ryanair's chief marketing officer Kenny Jacobs.
Yesterday, it said it carried a total of 10.4 million passengers in August, a record figure for the airline, and up 10% on the same time last year.
The airline said it will add extra flights on 14 routes from Dublin for next summer's schedule.
These include Alicante, Barcelona, Berlin, Birmingham, Brussels, Budapest, East Midlands, Liverpool, London Gatwick, Madrid, Malaga, Manchester, Venice Treviso and Warsaw.
In total, the airline will fly on 83 routes from Dublin and said it will deliver 70% of the growth at Dublin Airport this year.