He may be one of Ireland's wealthiest businessmen, he may be a former star pupil of Ryanair founder Dr Tony Ryan and he may have featured recently in some of Ryanair's more pointed advertisements.

But as far as Michael O'Leary is concerned, Denis O'Brien is irrelevant to the €1.45 billion offer for Aer Lingus.

Earlier this week it was announced that Mr O'Brien had spent €32 million buying a 2.1 per cent stake. While this triggered rejoicing among Ryanair's union opponents, Mr O'Leary yesterday appeared sanguine about the intervention of Mr O'Brien in this most extraordinary takeover battle. "It's a free market, everyone is entitled to buy shares. But it's not going to alter the outcome," said Mr O'Leary of Mr O'Brien.

He urged Mr O'Brien to read the Ryanair offer document to be issued on Monday, and said anyone who bought shares above the €2.80 Ryanair offer price was "not acting logically".

Throughout his presentation Mr O'Leary described Mr O'Brien as a "tax exile", and said he found it strange that Mr O'Brien described the idea of Aer Lingus and Ryanair coming together as "a disaster". "I don't think Denis actually has read the nature of our offer.

"I presume Denis is a little bit out of touch, given that I'd say he probably hasn't flown with Aer Lingus in quite a while since he bought the corporate jet, and certainly hasn't spent much time wandering around Dublin airport where Aer Lingus and ourselves have to deal with a Government-owned monopoly that is providing such a a shitty service to everybody."

He said Ryanair was committed to growing very aggressively and this included a flight to Malta for €22 return. "We are glad to say Denis can trade in the corporate jet and be able to fly between Malta and Dublin for just €22 return - a big saving on the cost of the Challenger 5 jet he's flying this week."

This was a reference to a recent report that Mr O'Brien used an address in Malta in a filing to the Companies Registration Office. This reference to Malta was later used in a Ryanair advert.