President Dilma Rousseff launched a poverty reduction program in 2011, but critics say this year's violent protests in Rio de Janeiro and other cities show income disparities pose a significant threat for both Brazilian politics and the economy.
The soccer World Cup will kick off in June in Sao Paulo, Brazil's business and industrial center. "The world's spotlight will fall on Sao Paulo over the next year as it prepares to host the opening match of the 2014 World Cup in June," Independent Catholic News said on its website.
"While billions of pounds are being spent to prepare for the tournament, 3.5 million people are still living in poverty in the city, and their needs are all too often being ignored," indcatholicnews.com said as it announced a fund-raising campaign by actress Jo Joyner.
Pope Francis warned during a visit to Brazil in July there could be no peace in a society that excludes some of its own members.
Critics say the Brazilian government has focused on building prestige projects before the World Cup and the 2016 Olympics but neglected to improve Brazil's economic and social infrastructures from the bottom up, creating potential flashpoints for more violent unrest among the country's millions of desperately poor.
"People in Brazil are absolutely delighted that they are hosting the World Cup in 2014, but what they are saying is -- if we can have world-standard football stadiums, why can't we have world-standard housing, world-standard healthcare, world-standard education?" Clare Dixon, from the UK Catholic Agency for Overseas Development said.
Dixon said the agency and its partners were helping local associations to ease the housing crisis among Sao Paulo's poor.
Slum dwellers in other Brazilian cities including Rio face similar problems.
A Forbes magazine survey of Brazil's income disparities produced sharp reaction from the local media and wealthy interest groups, who called the data simplistic.
The 124 richest people in Brazil hold assets that total $238.6 billion, or 12.3 percent of the country's gross domestic product, Forbes says.
Topping the Brazilian rich list is Jorge Paulo Lemann, 74, chief investor in the 3G Capital Fund, which recently purchased U.S. ketchup manufacturer Heinz and is a key shareholder at brewers AB-InBev and Burger King.
When Rousseff launched her poverty reduction program in 2011 some 16 million Brazilians were said to be living in extreme poverty, defined as having $30 and sometimes less a month to live on.