A row broke out on Twitter after Aer Lingus pointed out that a photo of one of its aircraft was being shown in a Ryanair advert.
Following a Twitter question on whether the airlines really do hate each other, Aer Lingus replied that it was just “healthy rivalry”, and encouraged Ryanair to agree.
However, Ryanair gave short shrift to the idea that the two airlines were even equals, the Telegraph reported.
“We stopped being rivals in the 90s. We’d have to treble our fares and lose 81m customers to be your rival #EuropesNo1,” it tweeted.
To which a disheartened Aer Lingus replied: “Okay, nevermind.”
The exchange on the micro-messaging site came ahead of a ruling expected today from the UK Court of Appeal on whether Ryanair will have to sell down its near-30% stake in the Irish flag carrier.
Ryanair has been told several times by competition regulators to slash its stake to no more than 5% but has appealed each time.
Ryanair has recently changed tack and said it is actively looking for a buyer for the stake, following two failed bids fro Aer Lingus by British Airways owner International Airlines Group.