Belarusian prosecutors opened a terrorism investigation against opposition leader Svyatlana Tsikhanouskaya, the latest move from authorities trying to quash opposition groups after months of anti-government protests.

Tsikhanouskaya, who fled Belarus in the aftermath of last August’s disputed presidential election, had no immediate reaction to the move, which was announced on March 29 by Prosecutor-General Andrey Shved.

In a statement, Shved alleged that Tsikhanouskaya and several other people plotted to plant explosives and arson attacks in Minsk and other cities several days ago.

There were no other details in the statement, although its announcement came days after officials said they arrested a person accused of attempting to stage explosions in Minsk and the nearby city of Barysau.

Belarus has been engulfed by protests ever since the August 9 vote, when Alyaksandr Lukashenka claimed a sixth term as president.

Opposition groups and some poll workers have said the election was rigged; the European Union, the United States, and other nations have refused to recognize the declared results.

In the wake of the vote, thousands of Belarusians took to the streets, in what became the largest and most persistent show of opposition in Lukashenka’s nearly three decades in power.

More than 33,000 people were arrested over weeks of demonstrations. Many of them were beaten by police and some have alleged being tortured while in custody.

In response to the repression, the West has slapped sanctions on top officials.

Last week, Tsikhanouskaya called for a new wave of anti-Lukashenka rallies. Police flooded Minsk and cracked down on opposition supporters who tried to launch rallies last week, arresting hundreds.