A crowd of furious Bosnian Muslims jumped fences and attacked Serbia's prime minister with stones and water bottles overnight, marring the 20th anniversary commemorations of the Srebrenica massacre.

Aleksandar Vucic, a former ultranationalist during the Balkan wars but who is now a moderate with a pro-Western stance, escaped serious injury. He said he was hit in the face with a rock as the crowds chanted "Kill, Kill" and "Allahu akbar," the Arabic phrase for "God is great."

The scenes overshadowed what was supposed to be a day of reflection and remembrance for the 8,000 Muslim men and boys slaughtered at the hands of Serb forces in the eastern Bosnian town of Srebrenica. Two U.N. courts ruled that the killings constituted genocide.

Vucic is among the most hated individuals for Bosnian Muslims, with some viewing him in worse terms than late strongman Slobodan Milosevic. During the 1992-95 Bosnian war, Vucic was an ultranationalist politician in opposition to Milosevic, criticising the Serb leader of leniency toward Bosnian Muslims.

Many Bosnian Muslims also still remember Vucic's incendiary statement during the Balkan wars that for every dead Serb, 100 Muslims should be killed. Some in the crowd held a banner with the quote to remind him of his past.

Vucic's security detail rushed him away, trying to protect him with bags, umbrellas and their raised arms from the projectiles raining down. His guards shoved through the angry crowd before pushing the prime minister inside an armored vehicle.

"We were attacked from all sides. It was well organized and prepared," a visibly shaken Vucic said upon his quick return to Serbia. He blamed hooligan soccer groups from Serbia and Bosnia for initiating the attack.

"I heard Muslim people telling the attackers 'why are you attacking him? It is not his fault. He had not done anything here.'"