Ryanair boss Michael O'Leary says the Greek people have elected "a bunch of lunatics".
The airline is in currently talks with the Greek government about carrying passengers free of charge there for the next two weeks - because people cannot use credit cards to book flights.
Ryanair has invested heavily in Greece, and Mr O'Leary said the company is growing strongly.
However, he criticised the Greek government, describing them as "lunatics".
"I think the Greek situation is a tragedy," he said.
"We're one of the largest investors in Greece at the moment, we're one of the few European companies that's actually growing strongly in Greece.
The difficulty we have in Greece, particularly on domestic flights, is that people don't have credit cards, they're not able to make payments.
"I mean, we're actually talking to the Greek government today about carrying people for free for the next two weeks on some of the domestic routes.
"the Greek situation is a tragedy, but, you know, the difficulty for the Greeks is that they've elected a bunch of lunatics."