Arrested Belarusian opposition blogger Roman Protasevich, who was on the diverted Ryanair flight, says he is cooperating and admitting to charges of organising protests in a video circulated by state TV channels on Monday.
The comments were immediately dismissed by his allies as made under duress.
The passenger flight from Athens to Vilnius was diverted while in Belarusian airspace on Sunday over a supposed bomb threat, prompting a global outcry to Minsk's forced landing of the aircraft.
"I am in Detention Centre no 1 in Minsk. I can say that I have no health problems, including with my heart or any other organs," Mr Protasevich said in the clip that appears to have been filmed on a phone camera.
The 26-year-old is wearing a black hoodie and sits behind a table in a nondescript room with a pack of cigarettes by his side.
He fidgets with his hands as he makes the statement and some dark markings are visible on his forehead.
"The attitude of employees towards me is as correct as possible and according to the law. I continue cooperating with investigators and am confessing to having organised mass unrest in the city of Minsk," he said.
Earlier, the Belarus Interior Ministry said Mr Protasevich was being held in Minsk and dismissed unconfirmed reports he was hospitalised with a heart condition.
"The administration of the institution has not received any complaints about his health," the ministry said on its Telegram channel.
Together with co-founder Stepan Putilo, Mr Protasevich until recently ran the Nexta telegram channels that helped mobilise protesters during the demonstrations that gripped ex-Soviet Belarus for months after a disputed election last August.
Protesters demanded the resignation of strongman Alexander Lukashenko, who has ruled Belarus for over two decades and secured a landslide victory in an election his opponents say was rigged.
The authorities unleashed a violent crackdown on protesters, detaining thousands, many of whom reported torture and abuse in custody. Several people died in the unrest.
Belarusians living in Poland and Poles supporting them hold up a placard reading 'Free Roman Protasevich' during a demonstration on 24 May 2021. Source: WOJTEK RADWANSKI/AFP via Getty Image
Exiled opposition leader Svetlana Tikhanovskaya, who ran against Mr Lukashenko in the election, also appeared in a similar video published by state media, urging her supporters not to protest.
Her allies said the video was made under pressure and that Ms Tikhanovskaya was threatened into recording it.
She soon fled to neighbouring EU member Lithuania.
"This is how Roman looks under physical and moral pressure," Ms Tikhanovskaya said on Twitter on Monday, commenting on the video, and called for his "immediate" release.
Mr Protasevich and Putilo, who both fled to Europe, were last year added to Belarus's list of "individuals involved in terrorist activity".
In Minsk, they face charges of causing mass unrest, an offence punishable by up to 15 years in jail.
EU response
EU leaders on Monday agreed to ban Belarus' airlines from the bloc's airspace and urged EU-based carriers not to fly over its airspace after Minsk forced a jet to land to arrest a dissident.
The leaders of the 27-nation bloc also called for the "immediate release" of Mr Protasevich and his girlfriend Sofia Sapega from detention, according to the conclusions of a Brussels summit, said an EU spokesman.
Western leaders accused Belarusian authorities of essentially hijacking a European plane, while Minsk claimed it had reacted to secure the flight after receiving a threat from Palestinian Islamist group Hamas to blow up the aircraft.
"There will be a very strong answer because it is outrageous behaviour and Lukashenko and his regime have to understand that this will have severe consequences," EU chief Ursula von der Leyen said as leaders from the bloc gathered.
The EU's push to punish Minsk came after Britain and Lithuania said they had issued instructions for their countries' aircraft to avoid Belarusian airspace, with London going further by banning Belarus's flagship carrier.
Ukraine said it would halt direct flights between the two countries and over Belarus, while Scandinavian airline SAS, Germany's Lufthansa and Latvia-based regional airline Air Baltic said they would be avoiding Belarusian airspace.
