Demonstrators attend a protest against Brazil's President Dilma Rousseff, part of nationwide protests calling for her impeachment, near the Rio Negro river in Manaus in Amazonas state, Brazil, March 13, 2016. [Photo/Agencies]

SAO PAULO/BRASILIA - Hundreds of thousands of Brazilians flooded the streets on Sunday in the biggest ever protests calling for President Dilma Rousseff's removal, reflecting rising popular anger that could encourage Congress to impeach the leftist leader.

The demonstrations were the latest in a wave of anti-government rallies that lost momentum late last year but have regained strength as a sweeping corruption investigation nears Rousseff's inner circle.

From the Amazon jungle city of Manaus to the business hub of Sao Paulo and the capital Brasilia, protesters marched in a nationwide call for Rousseff to step down, raising pressure on lawmakers to back ongoing impeachment proceedings against her that just a few weeks ago appeared to be doomed.

Police estimates from more than 150 cities compiled by news website G1 showed around 3 million Brazilians participated in the demonstrations. Some police estimates of previous protests have proved to be exaggerated.

Polling firm Datafolha estimated 500,000 demonstrators in Sao Paulo, the biggest rally in the city's history and more than twice the size of a major protest a year ago. The military police put the figure at 1.4 million at the height of the demonstration.

Government sources acknowledged the demonstrations were bigger than anti-government rallies in March 2015, which gathered as many as 1 million people.