Former colleagues of the dissident journalist arrested in Belarus after a Ryanair flight was diverted on Sunday say they now fear for their lives.
Roman Protasevich, 26, and his Russian girlfriend Sofia Sapega, 23, are both being held in detention.
“Roman is more in danger than other political prisoners in Belarus,” Stepan Putilo told the BBC.
Mr Protasevich has said he fears the death penalty after being placed on a terrorism list.
He faces charges related to his reporting of last August’s disputed Belarusian presidential election and the subsequent crackdown on mass opposition protests.
Belarus is the only European country that still executes prisoners.
Mr Putilo, who along with Mr Protasevich co-founded the opposition social media channel Nexta on the messaging app Telegram, said that while he had received death threats in the past, he was now “taking them seriously”.
Nexta has more than a million subscribers and was used for mobilising street protests last year.
Mr Protasevich and Ms Sapega were detained on Sunday, after Belarus scrambled a military jet to force their plane – flying from Athens to Vilnius, in neighbouring Lithuania – to land in Minsk, the Belarusian capital.
Western countries accuse Belarus of hijacking the Ryanair plane that was rerouted over a supposed bomb threat.
Addressing the Belarusian parliament on Wednesday, President Alexander Lukashenko defended the decision to divert the flight, citing the bomb threat, and said the West was “trying to interfere” in the country’s affairs.
“We need to take appropriate measures to protect our country,” he said, adding that he had acted within the law. “The West has moved from an uprising to ‘suffocation’ of Belarus.”
During his speech, Mr Lukashenko did not mention the arrest of Mr Protasevich.
‘We show what they want to conceal’
Mr Putilo told the BBC that the Belarus government under Mr Lukashenko “fears us because we show the truth”.
“We show what they want to conceal,” he said. “If the regime cares enough to bring down Roman’s plane, then we are doing something right, and we will carry on fighting.”