Belarusian authorities have opened a criminal investigation against one of the country’s most prominent human rights organizations and detained several of its members, in the latest crackdown on dissent against authoritarian leader Alyaksandr Lukashenka.

The Vyasna human rights center said March 5 that the Investigative Committee opened a case alleging the organization provides financing and other material support for unsanctioned mass protests and violating public order.

Four members of the center were also taken into custody.

Belarus has experienced near-daily protests since last August’s presidential election gave Lukashenka a sixth-term in a vote the opposition and West says was fraudulent and illegitimate.

Vyasna has been one of the main independent organizations keeping track of human rights abuses including torture, thousands of arrests, and political prisoners.

Security forces previously searched the group’s branches and detained and interrogated its members under separate investigations.

In a statement, Vyasna denied any wrongdoing and vowed to continue its work helping “victims of political repression and massive violations of human rights.”

“Vyasna has never been the organizer of any violent actions and has always supported the peaceful implementation of civil and political freedoms,” it said.

Vyasna has been defending human rights in Belarus for nearly 25 years, during which time it said it had been repeatedly pressured, intimidated, and persecuted by authorities.