Hungary launched a probe into Ryanair Holdings Plc after the government said Europe’s largest low-cost carrier raised ticket prices to pass on the costs of a windfall tax.

Prime Minister Viktor Orban is slapping an “extra profit” levy on a range of industries to fund utility price subsidies for Hungarians. The fee includes a newly introduced departure payment for airlines of 3,900 forint ($10) for travel within Europe.

“The government considers it unacceptable and rejects it in the strongest terms that Ryanair is deflecting the extra-profit tax onto passengers,” Economic Development Minister Marton Nagy said in a statement on Friday. “It’s especially egregious that Ryanair is starting to do this for already sold tickets.”

Ryanair has called on Hungary’s government to scrap the windfall tax, calling the levy “beyond stupid.” The carrier said unprofitable airlines were being hit at a time when they are struggling to recover from the Covid-19 pandemic and as they deal with the fallout from Russia’s war on Ukraine.

Critics of the windfall tax in Hungary have said the levy may fuel inflation as companies shift the burden onto consumers. Inflation topped 10% in May for the first time in 21 years.