Policemen clash with teachers during a protest in Curitiba in Parana state April 29, 2015. [Photo/Agencies]

Besides the protesters, at least two members of the press were also injured, according to daily O Estado de Sao Paulo. One was reportedly shot with rubber balls and the other was bitten by a police dog.

The protesters claimed that the changes in Parana Previdencia will be damaging to workers and will in time make the system unsustainable.

The state government denied it, saying that the changes will save money for the government and will maintain the balance of the system.