Ryanair has responded to the entry into the Irish market of no-frills rival Go by announcing a new service between Dublin and Edinburgh.
The move came just a week after Go said they would operate on the same route.
Ryanair reported plans for four return flights each weekday in what they claimed was "marking the arrival of really low fares in this marketplace for the first time".
Signalling the start of a prices war, the Irish airline said that for the first 29 days of the service, a return flight would cost £29.99, including taxes, and that same price would afterwards be guaranteed for at least 70% of seats on the route, with a highest fare of £99.99.
Ryanair chief executive Michael O'Leary says: "Everyone knows that Ryanair loves competition and any airline that wants to challenge us on the Irish market must actually sell low fares and not just talk about it."
He dismissed Go as "just another higher fare airline" adding: "If any so-called low-cost imitator wants to throw down a challenge to Ryanair on any of our routes, anywhere, any time and any price, then they may rest assured that we will meet every such challenge with more flights, guaranteed lower fares at every price level, and many thousands more seats every day at these lowest prices."
PA