The budget airline boss told a committee of Irish politicians that air traffic controller strikes happen on a Friday so that workers can have a three-day weekend.
During a three-hour committee appearance, Mr O'Leary made various charged comments.
He called on the European Commission to change laws so that only domestic French flights would be affected during air traffic controller strikes.
In July, flights from French airports faced disruption as airport workers went on strike to demand salary rises to keep up with inflation.
They also called for a recruitment drive to deal with resurgent travel demand, which has put airports and airlines under pressure this year after jobs were cut during the Covid-19 pandemic.
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“Many times, French air traffic controllers go on strike not because they want more pay, it’s because they don’t like (French President Emmanuel) Macron, or they didn’t like the result of the football match," Mr O'Leary told the Irish transport committee.
“All the strikes generally take place on Fridays, and then they don’t show up to work on the Saturday so they have a three-day weekend.”
He said that when French air traffic controllers go on strike, the French government uses minimum service legislation to protect domestic flights.
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“So, the French are all happily flying around the place. But it’s the poor Irish, the Spanish, the Italians and the Germans who are taking all of the cancellations.
“Our people, our citizens, our visitors are being completely screwed over while a bunch of French air traffic controllers go on strike — and we fully respect their right to go on strike — but let the French take the hit.
“It shouldn’t be Irish, Germans, Italians and Spanish who are not travelling to France [who] take the hit.”
Mr O’Leary also called for the proposed single European sky to be introduced, but said the European Commission “lacks the bottle” that earlier commissions had “to challenge the vested interests of the national governments”.
“It is bizarre that Europe’s free movement of people across Europe in a single market is allowed to be threatened by the French every time they have these recreational strikes, which they have frequently in the summer.
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“The technology now exists to allow us to fly straight, we should be allowed to fly straight.
"We would burn less fuel, we would reduce our impact on the environment and we would pass on enormous savings to our customers.
“In other words, they move to the same air traffic control system as America has, one system operate by all.
“The difficulty is that it’s opposed by every single air traffic controllers’ national union because it means less jobs for them, and therefore they can’t get national governments to agree to it.
“The European Commission lacks the bottle that those earlier Commissions had to challenge the vested interests of the national governments."
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Ryanair's only flights outside of Europe are to and from Morocco, Israel and Jordan.
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"We're talking to the Egyptians, the Libyans," Mr O'Leary told a Eurocontrol event, without giving any more details.
He said Ryanair would be the first airline to return to Ukraine when it was safe to do so.
Ryanair was one of the largest foreign airlines in Ukraine before it suspended all of its flights after Russia's invasion in February.