RYANAIR launched a summer fares price war with Aer Lingus after aggressively targeting the state airline's key sun destinations.
Michael O'Leary vowed that his airline will now undercut Aer Lingus on all their strategic Portuguese and Spanish departures as he launched seven new summer sun routes out of Cork.
All compete directly with existing Aer Lingus services, with Ryanair now basing a Boeing 737-800 at Cork specifically to service sun destinations.
The price war will come as a welcome relief to income-hit Irish families, with fares to some sun destinations now expected to drop by up to 30pc.
However, Mr O'Leary warned that there was "no prospect" of the summer routes being operated year-round, because of the Government's €10 tourist tax and "penal airport charges".
He said Ryanair only plans non-sun route growth for Kerry and Knock, because they have realistic charges compared to Dublin, Cork and Shannon.
Ryanair will only operate the new Cork routes for three months, saying that the move was partly underpinned by the collapse of Budget Travel and the fact that summer sun destinations are relatively immune to the Government's controversial €10 tourist tax.
"We will operate them for three months -- June, July and August. If they go, I'd say they could come back in 2011. If we can carry a lot of people from Cork to the sun in three months of the summer at a fraction of the fares charged by Aer Lingus, let's do it," he said.
"It serves two agendas -- one, it gives us more growth at Cork Airport, and two, it causes significant damage to our weaker and smaller competitors."
Ryanair claimed it will undercut Aer Lingus on some routes by up to 45pc -- but Mr O'Leary predicted that Aer Lingus will now slash prices in response.
Last night, Aer Lingus responded immediately to the Ryanair move and confirmed its 2010 summer schedule would be the largest ever.
In Cork alone, Aer Lingus will operate 140 weekly departures -- an increase of 44 flights a week on last summer's total.
The state carrier -- as well as operating its traditional routes to France, Spain and Portugal -- is planning new routes to Bristol, Cardiff, Edinburgh, Glasgow, Jersey, La Rochelle, London-Gatwick and Tenerife.
"We are very pleased to offer our low fares and quality service to an increased range of destinations. The support of the travelling public has helped us become Cork's largest airline and we look forward to welcoming more customers onboard in the coming months," Aer Lingus chief commercial officer Stephen Kavanagh said.
However, Irish holidaymakers hoping for a Ryanair entry to the trans-Atlantic market will remain disappointed.
Michael O'Leary ruled out any launch of a Ryanair 'sister airline' on the Ireland-US route until 2014 at the earliest because of the chronic lack of cheap, long-haul aircraft.