Speaking to the media O'Leary said that workers at the airline are welcome to join unions, but that according to Irish law the company does not have to recognise the unions.
He says the secret pilot network described in recent media reports is actually a front for pilots from other airlines, trying to bring Ryanair down.
But some Swedish politicians are calling for a boycott of the airline, for what they call its "anti-union" stand.
Josefin Brink is labour market spokesperson at the former communist Left Party. She is calling for a boycott of the airline. Speaking to Radio Sweden, she says the fact that the pilots have been forced to form the network anonymously is unacceptable. "We have the right to organise in Sweden, and in the EU" she says, "Ryanair have passed the limit of what can be seen as decent".
In a case in Norway a local court found that Ryanair staff, working for the company or a sub-contractor, are working for an Irish company, pay Irish taxes and social insurance, and even work on Irish territory as the planes are Irish, and Ryanair say they follow Irish labour laws. But that isn't good enough according to the Left Party's Brink.
The Social Democrats' Labour Market spokesperson, Ylva Johansson, says a boycott would be a good idea, but other measures are also needed, including introducing a social protocol on an EU level.