Riot police beat protesters with truncheons and riot shields and dragged people away in scuffles that injured as many as 15 people in the southern Buddhist region. Police arrested more than 85 people, authorities said.
More than 2,000 protesters marched into the central square of Elista calling on Ilyumzhinov to resign. The protesters were angered by high unemployment and accuse the president of violating human rights and stifling dissent.
Footage on state television showed protesters breaking through police barriers and throwing rocks.
"I have never before seen such a horrifying beating," said Semyon Ateyev, president of the Kalmykia Human Rights Center and one of the protest organizers.
"They pounded everybody they saw ... including women and kids. Then they started chasing people around the town," Ateyev said from hospital, where he was taken after being beaten by police.
Regional officials said most of those detained during the protest were drunk and would not face criminal charges.
Ateyev said the protest was part of a civil disobedience campaign aimed at ousting Ilyumzhinov, who they view as authoritarian and incompetent.
Ateyev said Ilyumzhinov, who heads the World Chess Federation and infamously met with Saddam Hussein's late son Uday, spends most of his time abroad "visiting kings and monarchs" and does not spend more than several days per month in his home region.
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