BRASILIA, Dec 12 (Reuters) - Supporters of far-right Brazilian President Jair Bolsonaro on Monday attempted to invade the federal police headquarters in the capital Brasilia, in a flash of post-election violence on the day the president's electoral defeat was certified.The violence unfolded after a Bolsonaro supporter was detained for allegedly organizing violent "anti-democratic acts," according to the judge who ordered his arrest.After months of baseless suggestions that Brazil's voting system is vulnerable to fraud, Bolsonaro has neither conceded defeat to Lula nor has he formally blocked the handover of power.SPARKED BY ARRESTThe violence in Brasilia came after Supreme Court Justice Alexandre de Moraes, who has led probes into Bolsonaro and his allies, on Monday ordered the temporary arrest of José Acácio Serere Xavante for allegedly carrying out anti-democratic acts.In a statement, the Supreme Court said Moraes "decreed the temporary arrest, for 10 days, of the indigenous José Acácio Serere Xavante, due to evidence of the commission of crimes of threat, persecution and violent abolition of the Democratic State of Law.""