The Swiss president on Sunday condemned the violence that erupted a day earlier when extreme-left groups halted a nationalist party's election rally, Accroding to AP. Up to 500 masked protesters blocked a 10,000-strong march through Bern by People's Party supporters hoping to hear party figures speak two weeks before national elections. Police fired tear gas and rubber bullets to disperse the protesters, who they said used «guerrilla tactics» to disrupt the event. Eighteen officers and three protesters were injured, and 42 people were arrested, police said. «I'm saddened by the images of violence,» Swiss President Micheline Calmy-Rey said in an interview with weekly Sonntags Blick, adding that extremists must not be allowed to prevent people from exercising their right to free speech. The People's Party has been criticized in recent months for its hard-line stance on immigration. Police said about 100 neo-Nazis had joined the People's Party march, which had to be diverted to another location on the outskirts of Bern _ Switzerland's medieval capital. «A few hundred extremists can't endanger our democracy,» Calmy-Rey said in the interview, appealing to all sides to stop playing on voters' fears in order to gain political advantage for the Oct. 21 polls.