BELGRADE, Yugoslavia: Violence erupted on the streets of Belgrade Tuesday when pro-government supporters clashed with opponents of Serbian President Slobodan Milosevic who had gathered for the 35th day to protest his invalidation of Serbia's local elections. The two rival groups pelted each other with mud, eggs and cabbages in Republic Square and attacked one another with lengths of pipe and clubs in the nearby streets. Hundreds of helmeted riot police eventually descended to break up skirmishes after the fighting escalated and one anti-government protester was shot in the head by a Milosevic supporter. Both sides held rallies attacking their rivals. An estimated 300,000 opposition demonstrators assembled in Republic Square, where they have met for more than a month to demand that Milosevic abide by the results of the November 17 municipal elections. Not far away, Milosevic supporters - many of whom were elderly people and blue-collar workers bused into Belgrade from out of town - denounced the anti-government protesters as traitors and chanted "We won't give up Slobo." Members of the opposition voiced their concern that the pro-government rally was a ploy by Milosevic's Socialist Party to spark a violent confrontation and give them an excuse for cracking down on opposition demonstrators. Opposition leader Zoran Djindjic urged his followers to exercise restraint: "We are stronger, and there is no reason to use force against them. That is exactly what Milosevic wants."