According to human rights activists, hundreds were arrested during the controversial constitutional referendum to consolidate the power of Belarusian ruler Alexander Lukashenko.
The human rights group Wesna listed the names of more than 300 people arrested on Sunday evening.
The videos published by the human rights activists show how people were taken away by police officers and larger groups demonstrated.
According to the electoral commission, 79.4 percent of those entitled to vote took part.
The opposition around civil rights activist Svetlana Tichanovskaya had previously criticized the fact that a vote was impossible under the conditions of political repression and the unfree media.
The constitution also provides for lifelong impunity for Lukashenko, who is accused of murder, torture and other most serious crimes against humanity.
Lukashenko is not recognized by the EU as President.
The presidential election in summer 2020 is considered fake.
Then there were mass protests.