A crowd throwing bottles and stones chased Serbia's prime minister from a ceremony in Bosnia on Saturday marking the 20th anniversary of the Srebrenica massacre, underscoring the depth of anger over Belgrade's continued denial of the crime as genocide.

Bodyguards whisked Aleksandar Vucic through angry mourners shouting and booing while a crowd surged up the hill behind the delegation as they ran for their cars. A Bosnian government source said the delegation had left the site.

The scene marred a ceremony to commemorate the day that Srebrenica, designated a safe haven protected by Dutch United Nations peacekeepers, fell to Bosnian Serb forces in the closing months of the 1992-95 war.