"If you look out long enough, I don't think Brexit has any affect on our business," O'Leary said at a Reuters Newsmaker event in London, adding that he thought Britain and the EU would reach a trade deal and retain the Open Skies aviation agreement.

"The UK's national interest is best served, I think, by staying in the European Union. It's nuts to leave it, but if you are going to leave, the first thing you've got to do on the day after you leave is renegotiate a trade deal with the European Union."

(Reporting by Conor Humphries and Tim Hepher; writing by Alistair Smout; editing by Laurence Frost and Jason Neely)