Ryanair and Aer Lingus are known for their healthy rivalry, but could this be one swipe too far?
Ryanair's Kenny Jacobs said that "in the greater context" Aer Lingus is "a bit of a side-show. It's a bit like Glenroe; it was big in the eighties but it doesn't really matter anymore."
It's not the first time the two airlines have clashed in public. This exchange was picked up by Twitter users in January.
Today's comment was made before the boss of IAG, the company looking to buy Aer Lingus, took questions from a panel of politicians.
IAG has offered €1.4BN to take over the company, but concern has been raised about the security of jobs and routes if the deal goes through.
Ryanair and the Government both own shares in Aer Lingus, and both are considering the offer but neither has come to a decision yet.
Willie Walsh, CEO of IAG, has admitted that he can't give any guarantees regarding jobs if the company is successful in buying Aer Lingus.
He has suggested that the potential takeover is a 'growth story' and Aer Lingus and its staff will benefit from the synergies in areas where jobs are duplicated.
Mr. Walsh said without IAG Aer Lingus is facing an uncertain future.
