Demonstrations gripped the country for months after authoritarian President Alexander Lukashenko, 66, claimed a landslide sixth presidential term in a vote the opposition and European leaders said was rigged.
Belarus has sentenced seven activists, including senior opposition figure Pavel Severinets, to jail terms of four to seven years, a journalist has reported from court.
In a trial held behind closed doors in a court in the eastern Mogilev region, the activists were found guilty of taking part in "mass unrest", referring to the historic protests that erupted after a disputed presidential election last August.
The demonstrations gripped the country for months after authoritarian President Alexander Lukashenko, 66, claimed a landslide sixth presidential term in the vote the opposition and European leaders said was rigged.
Severinets, who co-chairs the unregistered Belarusian Christian Democracy party, was arrested in June last year after a picket in support of opposition presidential candidates.
The court found him guilty of "organising mass unrest" even though he has been in detention for the past 11 months and did not take part in the mass demonstrations.
The court took two days to consider the case.
The European Union and the United States have sanctioned Lukashenko and his allies with travel bans and asset freezes over the crackdown on protesters.
Thousands were arrested, with many reporting torture in custody.
At least four people died during the demonstrations.
On Sunday, Belarus faced a global outcry after the government ordered the diversion of a European flight over Belarusian airspace and arrested a dissident who was on board.
Several EU-based carriers cut air links with Belarus while European leaders also warned of further sanctions on the ex-Soviet country.
Although the protests have since died down, activists and independent journalists continue receiving jail terms in the aftermath.
Meeting in Brussels on Monday, the 27 national leaders of the bloc demanded an immediate release of dissident journalist Roman Protasevich, as well as an investigation by the International Organization for Civilian Aviation into a Sunday incident during which Belarus forced a Ryanair flight to land in Minsk.
"We are closing our airspace to planes from Belarus and call on EU airlines not to fly over the country," said the head of the bloc's executive, European Commission President Ursula von der Leyen. "Further economic sanctions will be presented soon."
#EUCO leaders acted forcefully in response to the outrageous actions of the Belarus regime.— Ursula von der Leyen (@vonderleyen) May 24, 2021
We are closing our airspace to planes from Belarus & call on EU airlines not to fly over the country.
Further economic sanctions will be presented soon.
The upcoming sanctions may target oligarchs
The EU currently has a travel ban and an asset freeze in place on 88 Belarusians, including Alexander Lukashenko, and 7 companies, over Minsk's crackdown on protests following a contested presidential election last year.
Further individual sanctions could target oligarchs bank-rolling Lukashenko, diplomats said.
Lithuanian President Gitanas Nauseda said the new restrictions must be put in place immediately.
We welcome the sanctions imposed by the #EUCO against the regime in Belarus, for the state abduction of Roman Protasevich and Sofia Sapega.— David Sassoli (@EP_President) May 25, 2021
This is an unprecedented and extremely grave case that needs immediate responses. pic.twitter.com/3LMPU3WhfC
UN demands Belarus free journalist
The UN rights office on Tuesday demanded the immediate release of Belarussian journalist Roman Protasevich and his girlfriend after their flight was forced to land in Minsk.
"We call for the immediate release of both Roman Protasevich and Sofia Sapega, both of whom should be allowed to continue to their intended destination in Lithuania," spokesman Rupert Colville told reporters in Geneva.
Father of detained Belarus activist says son 'harmed'
The father of arrested Belarusian opposition blogger Roman Protasevich said Tuesday it was clear his son had been harmed from a video of him "confessing" to charges of organising protests.
"It's clear that he was physically harmed because you can see the signs of a beating on his face," Dmitry Protasevich told AFP.
The father said he thought Protasevich had some teeth missing.
"He was very nervous. He spoke in a way that was unusual for him. He would never speak like that. It's clear that he was reading something out that he was told to read out," he said.