A few thousand people have taken to the streets of Brazil's biggest city to protest over an 18-cent increase in bus and subway fares.

The Sao Paulo police department says on its Twitter page that some 2,000 are demonstrating peacefully in the city's downtown district. Police in Rio de Janeiro said about 400 people protested there.

The fare hike went into effect earlier this week, some 18 months after a 10-cent rise helped trigger historic nationwide demonstrations.

The June 2013 protests against higher transportation fares mushroomed into demonstrations against corruption, poor public services and the billions spent on last year's World Cup and the 2016 Olympics in Rio de Janeiro.