EU leaders are weighing a range of sanctions to punish Alexander Lukashenko’s Belarusian regime after what Brussels branded the “hijacking” of a Ryanair flight from Greece to Lithuania to arrest a dissident on board.

Options to be explored by the bloc’s 27 leaders at a meeting today include banning Belarus’s national carrier, Belavia, from landing at EU airports; declaring the country’s airspace unsafe; and extending sanctions such as travel bans and asset freezes already imposed on dozens of officials in Minsk over rights abuses, according to EU diplomats.

The forced landing in Minsk and subsequent detention of Roman Protasevich, former editor of Nexta, one of the main independent Belarusian media groups, was “yet another blatant attempt by the Belarusian authorities to silence all opposition voices”, said Josep Borrell, EU foreign policy chief. He called for an “international investigation” to ascertain any breach of international aviation rules.

Ursula von der Leyen, European Commission president, threatened “consequences” for the “outrageous and illegal behaviour of the regime in Belarus”. “Those responsible for the Ryanair hijacking must be sanctioned,” she tweeted. “Journalist Roman Protasevich must be released immediately.”

Belarus’s foreign ministry said such accusations were “baseless” while Russia’s called the EU response “shocking”.

Relations between Brussels and Minsk have deteriorated after last year’s presidential polls and the crackdown that followed. In December, European leaders imposed a new wave of sanctions on Lukashenko and other regime members.

Belarus is still part of the “Eastern Partnership” the EU has with six states close to Russia’s border, enjoying privileges such as a visa facilitation agreement launched last year. The European bloc had once hoped to draw Minsk from the Kremlin’s orbit, but Sunday’s events have underscored how that aim now appears forlorn.

Franak Viacorka, an aide to Belarus’s exiled opposition leader Sviatlana Tsikhanouskaya, called for a no-fly zone to be imposed over Belarus. He also urged further sanctions on Belarus’s lucrative oil and potash sectors, which provide crucial revenue for Lukashenko’s regime that has ruled Belarus with an iron fist for 27 years.

Belarusian media said Lukashenko personally gave the order to divert Ryanair flight FR4978, which was carrying 171 passengers from Athens to Vilnius on Sunday before abruptly rerouting to the Belarusian capital Minsk shortly before it was due to leave Belarusian airspace.

Belarusian officials said that a MiG-29 fighter jet had been scrambled to escort the airliner to Minsk following a bomb scare, which they later conceded was “false”.

In a statement posted on Belarus foreign ministry’s website on Monday, spokesman Anatoly Glaz said its aviation authorities had acted “in complete accordance with established international rules”. Glaz accused EU countries of “rushing to make openly warlike statements” and “deliberately politicising the situation with baseless accusations and labels”.

Russia’s foreign ministry, meanwhile, echoed Belarus’s attack on western countries’ responses to the incident, accusing them of hypocrisy.

“It is shocking that the west calls the incident in the airspace of Belarus ‘shocking’.” Maria Zakharova, the ministry’s spokeswoman, wrote in a post on her Facebook page, citing other examples of planes being diverted by western nations to arrest wanted people.

Ryanair chief executive Michael O’Leary said on Irish radio on Monday that Ryanair’s crew would give a detailed debriefing to Nato and EU authorities later on Monday. He was waiting for directions on whether to avoid Belarus airspace in the future, he said.

“It appears the intent of the authorities was to remove a journalist and his travelling companion,” he said, adding that he understood agents with the Belarusian KGB secret service may have been on board, but without offering any evidence.

Protasevich’s girlfriend, Sofia Sapega, who had been travelling with him, was also detained when the plane landed, according to the European Humanities University in Vilnius, where she was studying.

According to messages sent by Protasevich to colleagues on Sunday, he said he was being followed by a man he suspected was a Belarusian KGB agent while in the departure lounge in Athens.

Passengers on board the flight told AFP that Protasevich had begun rifling through his bags and had given some items to his girlfriend once it became clear that the flight was going to land in Belarus.

“[He was] not screaming, but it was clear that he was very much afraid,” Edvinas Dimsa, a passenger told AFP. “It looked like if the window had been open, he would have jumped out of it.”

Additional reporting by Philip Georgiadis in London and Richard Milne in Oslo