The violent scenes in the capital Brasilia underlined tensions in Latin America's biggest economy as the center-right government of President Michel Temer attempts to embark on major cutbacks.
Riot police yesterday fired tear gas and stun grenades into a crowd of thousands. Squads of officers occasionally beat and kicked isolated protesters.
Some demonstrators hurled objects at police and turned over a car. Thick clouds of tear gas eventually drove the crowds away but small groups continued to confront the security forces, throwing back tear gas canisters and attempting to block an avenue.
Even more controversial measures, including pension reform, are planned to follow. Temer says action is needed to save Brazil, deep in its worst recession for decades, from bankruptcy.
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The tensions also came amid national mourning after a plane crash late Monday in Colombia killed much of the southern Brazilian Chapecoense football team and 20 Brazilian journalists, among the more than 70 people who perished.
Flags outside Congress were at half-mast and earlier Temer declared three days of mourning.
However, last week there was uproar when deputies tried to change the text to include what would have amounted to an amnesty for any politicians who had accepted illegal campaign funds up until now. In the face of mounting public pressure, Temer announced that he would veto such a bill.