The state ceremony was also attended by Serbian PM Aleksandar Vučić and Republika Srpska President Milorad Dodik, who laid wreaths at the monument to the victims.
A minute of silence was also observed for all those killed in the NATO intervention.
On March 24, 1999, NATO planes began the 78-day air campaign. In the period from March 24, 1999 to June 9, 1999, during the NATO bombing campaign, 758 individuals lost their lives in air raids, the Humanitarian Law Centre stated.
The passenger train in the Grdelica Gorge, which was carrying civilians, was attacked on the second day of Orthodox Easter. Fifteen victims, who included children, have been identified.