Belarus forced a passenger plane carrying a wanted opposition activist to divert and land in its capital, provoking a furious outcry from world leaders who described it as an "act of state terrorism" ahead of an EU summit on Monday expected to toughen sanctions on Minsk.
Dissident journalist Roman Protasevich was detained on Sunday after Ryanair flight FR4978 was pulled from its Athens-to-Vilnius route and - accompanied by a Belarusian fighter jet - diverted to the capital city, state television reported.
Passengers described seeing the 26-year-old, who had been living in Poland, looking nervous as the flight was diverted to Minsk.
"He just turned to people and said he was facing the death penalty," Monika Simkiene, a 40-year-old Lithuanian, told AFP in Vilnius after landing - without Mr Protasevich - several hours later.
The incident comes as the European Union is set to discuss toughening its existing sanctions against Belarus, imposed over the crackdown by the regime of President Alexander Lukashenko on opposition protesters, at a pre-planned summit on Monday.
"The outrageous and illegal behaviour of the regime in Belarus will have consequences," EU chief Ursula von der Leyen tweeted, calling for Mr Protasevich's release, and adding those responsible "must be sanctioned".
Poland's Prime Minister Mateusz Morawiecki denounced Belarus's actions as "an act of state terrorism", while French Foreign Minister Jean-Yves Le Drian called for a "strong and united response" from the EU.
Lithuania and Latvia have called for international flights not to use Belarusian airspace.
The International Civil Aviation Organization - the UN's civil aviation agency - said the forced landing "could be in contravention of the Chicago Convention", which protects nations' airspace sovereignty.
Minsk's airport had released a statement earlier saying the plane had to make an emergency landing there following a bomb scare.
"The plane was checked, no bomb was found and all passengers were sent for another security search," said Nexta, a Belarus opposition channel on the Telegram messaging app, which Mr Protasevich previously edited.
Mr Lukashenko's press service said on its own Telegram channel the president had given the order to divert the flight and had ordered a MiG-29 fighter jet to accompany the plane.
It comes as Belarus authorities intensify their crackdown on the opposition following historic protests that gripped the ex-Soviet country after last year's disputed presidential election.
'Absolutely unacceptable'
The United States "strongly condemned" the arrest, with Secretary of State Antony Blinken calling for Mr Protasevich's release.
"This shocking act perpetrated by the Lukashenka regime endangered the lives of more than 120 passengers, including US citizens," he said in a statement, using an alternative spelling of the Belarusian leader's name.
He added on Twitter: "We demand an international investigation and are coordinating with our partners on next steps."
Australia's Foreign Minister Marise Payne condemned the "brazen" act and demanded an international investigation.
"This unprecedented action put innocent lives of airline passengers at risk and was a clear breach of the international standards that underpin civil aviation," Ms Payne said in a statement.
European leaders reacted with fury. In Athens, Prime Minister Kyriakos Mitsotakis tweeted: "The forced landing of a commercial plane to detain a journalist is an unprecedented, shocking act."
Lithuanian President Gitanas Nauseda described Belarus's actions as "abhorrent" and prosecutors said they had opened a criminal investigation for the hijacking of a plane.
The government in Ireland, where Ryanair is headquartered, described the incident as "absolutely unacceptable", while NATO called it "dangerous" and demanded an international investigation.
Since last August's disputed election, Belarusians have taken to the streets demanding the resignation of Lukashenko, who has ruled for over two decades.
Mr Protasevich and Nexta founder Stepan Putilo, 22, were added to Belarus's list of "individuals involved in terrorist activity" last year.
People shout slogans, as they attend a protest in Belarus earlier in the year. Source: AAP
The two - both now based in Poland - were accused of causing mass unrest, an offence punishable by up to 15 years in jail.
Belarus also labelled the Nexta Telegram channels and its logo "extremist" and ordered them blocked.
With close to two million subscribers on Telegram, Nexta Live and its sister channel Nexta are prominent opposition channels and helped mobilise protesters.
"It is absolutely obvious that this is an operation of secret services to capture the plane in order to detain activist and blogger Roman Protasevich," exiled opposition leader Svetlana Tikhanovskaya said on Telegram.
The opposition says that Ms Tikhanovskaya, who fled to neighbouring Lithuania after the election, was the true winner of last year's presidential vote.
KGB involved?
A member of the Nexta team, Tadeusz Giczan, said on Twitter that representatives of the Belarusian security agency had been on the flight with Mr Protasevich.
"Then when the plane had entered Belarus airspace, the KGB officers initiated a fight with the Ryanair crew insisting there's an IED onboard," he said.
A spokeswoman for state company Lithuanian Airports, Lina Beisine, said that Minsk airport had said the flight was redirected "due to a conflict between a member of the crew and the passengers".
In a statement - that did not mention Mr Protasevich - Ryanair said the flight's crew had been notified by Belarus air traffic control of "a potential security threat onboard" and were instructed to divert to Minsk, the "nearest" airport.
Lithuanian Foreign Minister Gabrielius Landsbergis said there were 171 passengers aboard the flight, most of them Lithuanian nationals.
The EU and the United States have sanctioned Lukashenko and dozens of officials and businessmen tied to his regime with asset freezes and visa bans.
The opposition protests in Belarus, which left at least four people dead, have now subsided, but journalists and activists continue to receive prison sentences in the aftermath.
