Ryanair said Monday it would follow European aviation regulators’ advice on whether to avoid Belarus airspace. The Ireland-based airline’s chief executive called the diversion “a case of state-sponsored hijacking.”

Belarusian President

Alexander Lukashenko

scrambled a jet fighter Sunday to force a Ryanair commercial aircraft to land in Minsk, where a journalist and opposition activist was detained. The incident sparked an international outcry and raised questions over the legality of the plane’s grounding.

The aircraft was flying from Athens to Vilnius, Lithuania, when it was diverted to land in the Belarusian capital.

Ryanair said the flight’s crew were notified by Belarusian air-traffic control of a potential security threat on board and were instructed to divert to the nearest airport, which was Minsk.

Speaking to Irish radio, Ryanair Chief Executive

Michael O’Leary

said the airline was debriefing the crew and added that they did a “phenomenal job to get that aircraft and almost all the passengers out of Minsk after six hours.”

Mr. O’Leary said the incident was “very frightening” for passengers and crews, saying they were held under armed guard and had their bags searched.

He told Ireland’s Newstalk radio channel that, “It appears the intent of the authorities was to remove a journalist and his traveling companion.”

Calls have grown from European politicians—including in Ireland—for flights to be banned over Belarus. Mr. O’Leary said his airline would take guidance from European authorities about whether that should happen.

However, he said they don’t fly over Belarus much and that it would be a “very minor adjustment” to fly over Poland instead.

Write to Benjamin Katz at ben.katz@wsj.com