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.

Key points: An estimated 500,000 demonstrators flooded into Sao Paulo

An estimated 500,000 demonstrators flooded into Sao Paulo Protesters call on Congress to impeach President

Protesters call on Congress to impeach President Protests took place nationwide

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 Ms 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 Ms Rousseff to step down, raising pressure on politicians 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 that about 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.

In the skyscraper-lined Avenue Paulista in Sao Paulo, a sea of protesters wearing Brazil's national colours of yellow and green chanted "Dilma out" and waved banners that read "Stop the corruption" while music blared from nearby trucks.

"The country is at a standstill and we are fighting to keep our company afloat," said small business owner Monica Giana Micheletti, 49, at the Sao Paulo demonstration.

"We have reached rock bottom."

President insists she will not quit

Protesters in Rio have called for the President to be removed following allegations of corruption. ( ABC: Mary Gearin )

Many blame Ms Rousseff for sinking the economy into its worst recession in at least 25 years.

Opinion polls show more than half of Brazilians favour the impeachment of the President, re-elected for a second four-year term in 2014.

Ms Rousseff, who insists she will not quit, is the latest leftist leader in Latin America to face upheaval as a decade-long commodities boom that fuelled breakneck growth and social spending comes to an abrupt end.

Ahead of the demonstrations, tensions were high after Sao Paulo state prosecutors requested on Thursday the arrest of Ms Rousseff's predecessor and political mentor, Luiz Inacio Lula da Silva, on money-laundering charges.

A judge still has to decide on the request, which can be rejected.

If Ms Rousseff is impeached by Congress, Vice-President Michel Temer — the leader of the main coalition partner, the Brazilian Democratic Movement Party (PMDB) — would take office.

In an effort to analyse the fallout from the protests, Ms Rousseff met with a handful of ministers at her home in Brasilia, a presidential aide said.

Ms Rousseff's press office welcomed the peaceful nature of the demonstrations, saying it reflected the maturity of the country's democracy.

Small groups of a few hundreds of her supporters wearing red shirts also marched in several cities.

Reuters