Thirty people were injured and 22 more arrested during dramatic events outside Congress where union movements, political parties, picket groups, NGOs and individual citizens flocked to protest a Lower House vote on the national government’s pension reform bill.
An estimated 1,000 police in riot gear shot tear gas and rubber bullets at stick-wielding protesters who torched several garbage bins outside Congress and in nearby streets.
Union leaders and social activists say the reform measure will reduce pension and retirement payments as well as aid for some of poor families starting in March.
"Congress has never lived through a state of militarisation like the one that we lived today," said opposition lawmaker Agustin Rossi, adding that he had been hit by tear gas.
"If the government has a fiscal problem, it should resolve it without putting a hand in the pockets or the pensioners," he said.
Argentina's largest union had threatened to stage a general strike if the measure was approved. The bill, which already passed in the Senate, is part of a series of reforms launched by the government of President Mauricio Macri to reduce Argentina's high deficit.
Macri took office in December 2015 promising to cut bloated spending and revive Argentina's struggling economy. But his ordering of job cuts, the elimination of tariffs aimed at protecting local industry and the slashing of utility subsidies have fueled labor unrest in a nation with a long tradition of generous state jobs and benefits.