Demonstrators in Minsk have been arrested while demanding the release of colleagues detained the day before.
A group on Sunday called “Students of Belarus” called for the activists to be freed claiming they were wrongly arrested.
But police responded by making further arrests.
There is much public anger in Belarus over falling living standards and an unpopular tax on the unemployed.
Police on Saturday used force to detain large numbers of people including protesters, passers-by and several journalists.
Although earlier demonstrations had passed off peacefully, last week President Alexander Lukashenko hardened his stance and called the protesters “scumbages” and accusing them of trying to oust him.
The crackdown has drawn sharp criticism from the European Union and rights groups.