POTOCARI, Bosnia — 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. During the 1990s, Vucic was a disciple of the “Greater Serbia” ideology that fueled much of the bloodshed that accompanied Yugoslavia's demise. He has since rebranded himself as pro-Western and his attendance on Saturday was intended to be symbolic of how far the region has come since wars that left at least 135,000 people dead, 100,000 of them in Bosnia. “Look at him (Vucic) and look at those thousands of tombstones,” said Hamida Dzanovic, who had come to bury two bones identified by DNA as those of her missing husband. “Is he not ashamed to say that this was not genocide? Is he not ashamed to come here?” she asked, recalling the last time she saw her husband. “I remember him returning twice to kiss our children, like he knew we would never see each other again.” — Reuters