Belgrade, 24 September (RFE/RL) - Riot police tonight set up lines to separate supporters and opponents of Yugoslav President Slobodan Milosevic, who gathered in the city center following presidential and parliamentary elections. Polls have closed and vote counting has began. Milosevic's main opponent is Vojislav Kostunica, who led pre-election opinion polls. An independent election monitoring group said there were major voting irregularities, but no reports of election disruptions. The opposition claims from its unofficial observations that there was a turnout of some 75 percent. In the Yugoslav constituent republic of Montenegro, Misko Vukovic, an adviser to President Milo Djukanovic, told Associated Press that turnout was below 20 percent. Montenegro's pro-western leadership called for a boycott of the elections in that republic.