The rival protests sweeping Brazil have exposed a demographic divide between President Dilma Rousseff's haters and backers, igniting a national debate about race and class that is only increasing tensions.

Waving the red banners of the ruling Workers' Party, Rousseff's left-wing base sought to seize back the streets this week, after tides of protesters draped in the yellow and green of the national flag marched nationwide last Sunday calling for her impeachment.

Riot police in Brazil broke up an angry anti-government protest Friday as President Dilma Rousseff's supporters mobilized for a rival show of force against impeachment proceedings launched by her enemies in Congress.

With the leftist leader fighting calls to quit and financial markets apparently betting on a collapse of her government, Rousseff's embattled left-wing base has vowed to take to the streets.

Protesters, many draped in the Brazilian national flag, poured into the streets of Brasilia and Rio de Janeiro on Sunday at the start of mass demonstrations seeking to bring down President Dilma Rousseff.

More than a million people were expected to turn out across the nation, which will host the Summer Olympics in Rio de Janeiro this August.

Torrential rains overnight killed at least 15 people on the outskirts of the Brazilian economic capital Sao Paulo, rescue workers said Friday.

Ironically, the flooding comes on the heels of two years of drought that caused severe water shortages in the sprawling metropolis of 20 million people.

Police briefly detained Brazil's powerful ex-president Luiz Inacio Lula da Silva for questioning and searched his home Friday as part of a probe into a huge corruption scheme at state oil company Petrobras.

Agents searched Lula's house in Sao Paulo, the offices of the Lula Institute, and houses of family members and associates, said Jose Chrispiniano, a spokesman for Lula and his institute.

Police in Rio de Janeiro tortured five young people, aged between 13 and 23, on Christmas night, allegedly burning them and sexually molesting them after demanding extortion money, local media reported Sunday.

The young people were riding home from a party on motorbikes when the police stopped them allegedly for not wearing their helmets, the Rio daily O Dia said.

Brazil's Supreme Court ruled Thursday that Congress must restart impeachment proceedings against Dilma Rousseff from scratch and overhauled the procedure, in a badly needed win for the embattled president.

In an 8-3 decision, the judges annulled an opposition-dominated impeachment commission established by secret ballot in the lower house last week and ordered the procedure be restarted in an open vote.

Supporters of embattled President Dilma Rousseff marched across Brazil on Wednesday protesting what they say is a "coup" aimed at toppling the leftist leader by impeachment.

"There will be no coup!" chanted thousands of marchers in downtown Sao Paulo, most of them wearing the red shirts of Rousseff's Worker's Party (PT).

After an eight-month investigation, Rio police this week dismantled a network that had provided 72 Syrian immigrants with fake Brazilian identification documents, news reports said Wednesday.

The network had provided the Syrians with birth certificates, identity cards, voters' cards and passports, according to the government news agency Brasil.

Thousands of Brazilians took to the streets Sunday to demand that embattled President Dilma Rousseff -- facing a weak economy and calls for her impeachment -- be removed from office.

Rousseff is fighting for her political life, standing accused of illegal budgeting maneuvers that she says were long-accepted practices by previous governments.