A Belarusian man jailed over a satirical drawing of President Alexander Lukashenko has died in prison, independent human rights group Viasna reported Sunday.

Since the 2020 protests against his re-election, Lukashenko has doubled down on repressing critical voices, jailing or forcing them into exile.

Viasna reported on Telegram that Nikolai Klimovich died in penal colony number 3 in Belarus' northern Vitebsk region.

In February 2023, a Belarusian court had found the 61-year-old guilty of "insulting" the Belarusian leader over a satirical picture posted on social media.

A judge sentenced him to a year in prison, despite the fact that Klimovich suffered from a serious heart disability, Viasna said.

Opposition leader Svetlana Tikhanovskaya said she was "heartbroken by the news."

"If we don't get urgent medical help to political prisoners, more will die," Tikhanovskaya said.

A self-proclaimed dictator, Lukashenko has ruled Belarus since 1994.

His regime, reclusive for years, has become even more isolated after brutally suppressing protests and allowing Russia to use Belarusian territory to launch its Ukraine offensive.

Viasna recorded almost 1,500 political prisoners in the country.