Brazilian riot police on Friday fired tear gas and stun grenades to disperse a violent protest against a rise in public transport fares in the country's largest city, Sao Paulo.
Television images showed small groups of rock-throwing, masked youths clashing with police in the center of the metropolis, amid burning piles of rubbish. Protesters smashed the windows of buses and vandalized bank agencies.
Many Sao Paulo residents have been angered by the increase in public transport prices, with inflation in Brazil already running at more than 10 percent.
More than 1.5 million Brazilians lost their jobs in the year to November, as Latin America's largest economy edged deeper into its worst recession in more than 25 years.
The march gathered thousands in Sao Paulo's downtown area and quickly turned violent when masked youths threw rocks at police. There was no immediate information about arrests or injuries.
Police also clashed with protesters in the city of Rio de Janeiro later on Friday. Television images showed masked protestors spray painting buses and smashing their windows.
The scenes evoked protests that swept Brazil in 2013, sparked by anger over bus fare increases, that brought hundreds of thousands of people onto the streets.
The demonstrations come as left-leaning President Dilma Rousseff, whose popularity has been crushed by the recession and a sweeping anti-corruption investigation that has ensnared her ruling coalition, faces impeachment proceedings in Congress.
Some political analysts say the mood on the streets toward her government could play an important role in determining the outcome of the impeachment process.