Western powers have prepared to pile sanctions on Belarus and cut off its aviation links, furious after it scrambled a warplane to intercept a Ryanair aircraft and arrest a dissident journalist, an act one leader denounced as "state piracy".
In a video posted online, detained blogger Roman Protasevich, 26, said he was in good health, being held in a pretrial detention facility in Minsk, and acknowledged having played a role in organising mass disturbances in the capital last year.
In the video on Telegram, he wore a dark sweatshirt and clasped his hands tightly in front of him. The comments were dismissed by his allies as having been made under duress.
A Polish deputy foreign minister, Pawel Jablonski, told broadcaster TVN24 his government had heard from Protasevich's mother about his being in poor health.
Belarus's interior ministry said Protasevich was being held in jail and had not complained of ill health.
European Union leaders meeting in Brussels on Monday called for Belarusian airlines to be banned from the bloc's airspace and urged EU-based carriers to avoid flying over the former Soviet republic.
They also agreed to widen the list of Belarusian individuals they already sanction and called on the International Civil Aviation Organisation (ICAO) to urgently investigate Belarus forcing a Ryanair plane to land in Minsk on a Greece-Lithuania flight on Sunday.
The EU and other Western countries also called for the release of Protasevich, who was detained when the plane landed.
Irish Foreign Minister Simon Coveney, using language that was echoed by a number of other EU countries, said: "This was effectively aviation piracy, state sponsored."
Protasevich's social media feed from exile has been one of the last remaining independent outlets for news about Belarus since a mass crackdown on dissent last year. Sofia Sapega, a 23-year-old student travelling with him, was also detained.
Britain said it was instructing British airlines to cease flights over Belarus and that it would suspend the air permit for Belarus's national carrier Belavia with immediate effect.
KLM, the Dutch arm of carrier Air France KLM, would temporarily halt flights, Dutch news agency ANP reported.
German airline Deutsche Lufthansa later said it would avoid Belarusian airspace until further notice.
Still, the options for Western retaliation appear limited.
The Montreal-based ICAO has no regulatory power, and the EU has no authority over flights taking off and landing in Belarus or flying over its airspace, apart from direct flights that originate or land in Europe.
Belarus lies on the flight path of routes within Europe and between Europe and Asia, and skirting Belarus would slow flights down and cost airlines money.
The EU and the United States imposed several rounds of financial sanctions against Minsk last year, which had no effect on the behaviour of authoritarian President Alexander Lukashenko, who withstood mass demonstrations against his rule after a disputed election.
Since the disputed vote, authorities rounded up thousands of his opponents, with all major opposition figures now in jail or exile.
NEXTA, a news service where Protasevich worked before setting up his own widely followed blog, ran an interview with his mother, who said that as soon as she heard reports of a bomb scare on a flight, she knew it was a plot to capture him.
"I just want to say that my son is simply a hero, simply a hero," Natalia Protasevich said, weeping. "I truly hope that the international community will wake up for him."
Belarus says it acted in response to a false bomb threat by Palestinian militant group Hamas. A Hamas spokesman denied the group had any knowledge or connection to the matter.
Belarus said its ground controllers had given guidance to the flight but had not ordered it to land. State media said the intervention was ordered personally by Lukashenko.
Ryanair boss Michael O'Leary, who referred to the incident as a state-sponsored hijacking, said he believed security agents had been on the flight.
Lithuanian authorities said five passengers never arrived, suggesting three others besides detainees Protasevich and Sapega had disembarked in Minsk.
Russia, which has provided security, diplomatic and financial backing to Lukashenko, accused the West of hypocrisy.
Australian Associated Press