Huge protests break out across Brazil

Some 3.3 million people across Brazil marched on streets to demonstrate on Sunday against the government over corruption and an economic downturn.

The protesters marched in more than 200 cities, carrying placards, banners and balloons reading "Dilma Out, PT Out," in reference to President Dilma Rousseff and the ruling Workers' Party.

Uniformly dressed in yellow and green, the colors of Brazil's flag, the demonstrators demanded the resignation of the president and the arrest of her predecessor Luiz Inacio Lula da Silva.

Sao Paulo, Rio and Brasilia saw the largest gatherings of protestors.

In Sao Paulo, Brazil's largest city, some 1.4 million people took part in the protest, according to local authorities. Private-owned news network Globo said the march extended "more than two kilometers."

In Rio de Janeiro, around 1 million people participated in the demonstration, organizers estimated.

Nearly 50,000 people gathered around the National Congress building in the capital Brasilia, chanting "Dilma Out."

The protesters expressed firm support for the graft probe into alleged corruption at state-controlled oil and gas giant Petrobras. The probe, lasting two years, so far has led to arrests of many politicians, former Petrobras executives and executives of construction companies which made fraudulent contracts with Petrobras.

They also called for the arrest of Lula, who was recently questioned by police over the investigation. The former president has been charged with money laundering and hiding assets.

Sao Paulo state prosecutors requested on Thursday preventive arrest of Lula, but the judge in charge of the case has yet to approve or reject it. The preventive arrest is an instrument used under Brazilian law when there is a risk that the accused in a process will try to flee, tamper with evidence or threaten witnesses.

In anticipation of the protests, Rousseff held a press conference on Friday, refusing to quit.

"No one has the right to demand the resignation of a legitimately elected president without providing proof that she has violated the Constitution," said Rousseff.

In addition to the corruption probe, the president is under pressure of impeachment, as lower house Speaker Eduardo Cunha is expected to form a commission to begin impeachment proceedings over allegations of fiscal mismanagement in the week to come.

The demonstrators also vented their anger on members of opposition Brazilian Social Democracy Party (PSDB).

Geraldo Alckmin, governor of Sao Paulo state, and Aecio Neves, former presidential candidate who narrowly lost the 2014 election to Rousseff, were jeered at as they tried to join a protest march in Sao Paulo. Endi