SAO PAULO (AFP) - Brazil deployed special federal police on Wednesday to protect Confederations Cup venues, as mass "Tropical Spring" protests against government spending for the 2014 World Cup turn violent.

A day after more than 250,000 people took to the streets of major cities in mostly peaceful rallies, Brazil's President Dilma Rousseff tried to get ahead of a wave of protests and publicly vowed on Tuesday to listen to the complaints.

But authorities were also taking no chances as protests turned violent in Sao Paulo and threatened to turn violent in other cities.

The National Force, a special federal police force called up in cases of social unrest, will be sent to five of the six cities where the Confederations Cup football tournament is being played, Agencia Brasil reported on Wednesday, citing the Justice Ministry.

The government reaction is notable given that the Confederations Cup is seen as a dry run for the World Cup next year.

The National Force, composed of police and firefighters from different states that are called up for duty on special occasions, is a "conciliatory, mediating" force, "not repressive," the Justice Ministry said.

National Force police however were not in a conciliatory mood on Sunday when they fired tear gas and rubber bullets at protesters in Rio de Janeiro outside the Maracana stadium.

The Confederations Cup opened on June 15 and lasts for two weeks. Eight national teams from around the world are participating.

More protests are expected on Wednesday in Fortaleza, in Ceara state, and Thursday in various Brazilian cities.

In all, Brazil is set to shell out some US$15 billion (S$19 billion) on sporting events through to the World Cup in 2014. Rio de Janeiro, where real estate and rental prices have soared to exorbitant levels, will also host the 2016 summer Olympics.