Sixty-year-old Bialiatski, who founded Viasna, and several other political activists are accused of smuggling a "large amount of cash" into Belarus to allegedly fund opposition activities, his rights group said in a statement.

Bialiatski, his deputy Valentin Stefanovich and another activist, Vladimir Labkovich, have been in detention since July, 2021. They were initially accused of tax evasion.

"They face between seven and 12 years of imprisonment," Viasna said.

The rights group said that the criminal case went to court but the date of the beginning of the trial had yet to be set.

Bialiatski's organisation, which means "Spring" and was founded in 1996, is Belarus's most prominent rights group.

Supporters see the jailing of Bialiatski and his associates as a thinly veiled tactic to silence their work.

Citing prosecutors, Viasna said the rights activists are accused of smuggling into Belarus at least 201,000 euros and $54,000. The money has been used to help activists pay off their fines, among other purposes, the statement said.

Bialiatski and his associates were jailed after large-scale demonstrations against the regime in 2020, when authoritarian President Alexander Lukashenko claimed victory in elections the international community deemed fraudulent.

Bialiatski has battled against repression for a quarter of a century and spent years in jail for his efforts.

He spent his 60th birthday in prison on September 25, as he did his 50th.