Reclusive Belarus on Monday freed five political prisoners in a rare amnesty by President Alexander Lukashenko, who has waged a crackdown on opponents throughout his three-decade rule.
Lukashenko intensified that campaign when huge nationwide protests erupted after he claimed victory in a 2020 presidential election that rights groups said was fraudulent.
Leading rights group Viasna estimates that Belarus has more than 1,400 political prisoners -- including its founder, Nobel Peace Prize winner Ales Bialiatski -- with thousands more having fled the country.
"Today we witnessed the first cases of some political prisoners being released in Belarus," exiled opposition leader Svetlana Tikhanovskaya posted on X.
Viasna said three men and two women were released in the amnesty.
It named one man as 67-year-old Rygor Kastusev, leader of the banned National Front party, who was arrested in 2021 after standing against Lukashenko in the 2010 presidential election.
Viasna also said two more men and two women were being released but could not yet reveal their identities for security reasons.
There was no official statement from Minsk or coverage on major state media of the amnesty, but Lukashenko had said a day earlier it was likely.
He told reporters on Tuesday "not to be surprised" if some political prisoners with serious illnesses who were arrested over the 2020 protests were released in the coming days.
"They are really seriously ill, mostly with cancer," the Belta state news agency quoted him as saying.
"I am glad to see these people free and reunited with their loved ones," Tikhanovskaya added, but said "many" were still behind bars.
"More than 200 political prisoners in Belarus are in critical health conditions," she said on Tuesday, after Lukashenko's comments.
"Already, at least six have died behind bars. They must be released unconditionally. Their urgent release is not a political issue, but a humanitarian one," Tikhanovskaya said.
Lukashenko, who will mark 30 years as president this month, was attending a military parade in Minsk on Wednesday, where he compared the European Union and United States to Nazi German leader Adolf Hitler.
For years he tried to balance relations between Russia, Belarus's key ally, and the European Union.
But that broke down in 2020 when his riot police waged an unrelenting crackdown on peaceful protests after he claimed victory in a presidential poll marred by widespread allegations of fraud.
At the height of the August 2020 protests he flew over crowds of demonstrators in a helicopter, wearing riot gear and carrying an assault rifle, footage released by his office showed.
And in 2022 he allowed Russia to use Belarus as a launching pad for its invasion of Ukraine, resulting in a wave of Western sanctions being placed on his country.
Tikhanovskaya's husband, Sergei Tikhanovsky, is among those jailed in Belarus.
A spokesperson for Tikhanovskaya told AFP there was no talk of him being among those released.
Tikhanovskaya stood against Lukashenko in the 2020 presidential election in place of her husband, a popular anti-Lukashenko campaigner, who was arrested after announcing his plan to run.
She claimed victory in the eventual vote and fled to EU member Lithuania.
Other opposition leaders, including Maria Kolesnikova, who tore up her passport as authorities were trying to force her to leave the country, have been sentenced to more than a decade behind bars.
From exile, Tikhanovskaya has continued to campaign against Lukashenko, including over his support for Russian President Vladimir Putin's invasion of Ukraine.
