“The High Commissioner has called for the immediate release of all unlawfully detained and for an immediate, thorough, independent and impartial investigation into all allegations of human rights violations,” the agency's website said in a statement.
Bachelet also expressed the view that everyone who has been “ill-treated” should be compensated.
“The right to peacefully protest online must also be protected,” she said.
Earlier in the east of Minsk, several dozen people formed a "chain of solidarity" with those who suffered during the protests in Belarus.
The Ministry of Internal Affairs of Belarus announced the arrest of more than 1,000 people during mass actions throughout the country on the night of August 11-12.