Serbian Prime Minister Aleksandar Vucic and Croatian President Kolinda Grabar-Kitarovic arrived in Srebrenica to mark the 20 years of Europe's worst massacre since the Holocaust.
Former US President Bill Clinton was also amongst those to arrive for the memorial ceremony.
Over 50,000 people were expected to mark the anniversary and attend the funeral of its 136 newly-discovered victims.The remains of Srebrenica victims are still being found in mass graves with some seven thousand victims already excavated from 93 graves or collected from 314 on-surface locations and identified through DNA technology.
In July 1995, Bosnian Serb forces killed more than 8,000 Muslim men and boys in a designated United Nations 'safe haven,' the eastern Bosnian enclave of Srebrenica,
Around 15,000 men and boys managed to escape and fled through the woods, but many were murdered by the Serbian army who ambushed them disguised as UN soldiers
Bosnian Serb army commander Ratko Mladic, who orchestrated the capture of Srebrenica, was arrested in Serbia in 2011 after 16 years on the run.
He is accused of genocide for orchestrating the massacre and for his role in the siege of Bosnia's capital Sarajevo.
War had broken out in Bosnia in April 1992. The Bosnian Serb army (VRS) swept eastwards. Srebrenica, a town of 36,000 where Muslims made up 75 percent of the population, was taken over by Serb troops but Muslims regained it after several weeks.
Early in 1993, Serbs started an offensive on Muslim-held areas. Srebrenica and Zepa became isolated enclaves deep in Serb-held territory. Muslims from the area flocked to Srebrenica and the population swelled to 60,000. They had little food, water or medical supplies.
Thousands of Muslim men and boys were slaughtered by Bosnian Serb forces after they captured Srebrenica in July 1995 near the end of Bosnia's inter-ethnic war, in the worst atrocity on European soil since World War II.