The Youth Initiative for Human Rights remembered the victims of the Srebrenica genocide 23 years ago in a park outside Serbia’s Presidency building in Belgrade on Wednesday night.
The participants lit candles at the age of the fountain, carrying a banner reading "We will not forget the Srebrenica genocide".
The police encircled the activists, separating them from a group of a dozen demonstrators carrying Serbia’s flag.
They called on Serbia's politicians to join them, but no one showed up.
Earlier in the day, the activists of the Initiative repainted the graffiti celebrating the Bosnian Serb wartime military leader General Ratko Mladic, convicted of war crimes in the 1992-1995 Bosnian war and the Srebrenica genocide in the first instance.
He is sentenced to life imprisonment but appealed the verdict.
On Tuesday night, another Serbia's NGO also marked the Srebrenica genocide anniversary.