By Tom Gibb BBC correspondent in Sao Paulo

Go to any bus station in the miles and miles of slums and suburbs that surround Sao Paulo, and you will find a large proportion of the faces are black.

Look at the election posters now littering the streets for the thousands of candidates standing in Sunday's general elections - and there is hardly a black face to be seen.

Front-runner Luiz Inacio Lula da Silva has been courting the black vote

Brazil has always prided itself on being a racial democracy - but more and more Brazilians are becoming aware that may be a myth.

The statistics tell the story: black or mixed Brazilians represent 45% of the population.

But nearly two-thirds of black Brazilians live below the poverty line. They are more likely to be unemployed and they earn less.

As one goes up in the education system there are fewer and fewer black faces.

One of the few exceptions in the University of Sao Paulo communications school is Rosangela Malachias, a doctoral student who is also a beneficiary of one of the few affirmative action programmes in Brazil.

Brazilian society and the federal government do not like to discuss racism

Rosangela Malachias, doctoral student

She gets a small government grant to help prepare for exams to become a diplomat.

"Imagine I have never had a black professor - how is that possible in Brazil?" she said.

"In my opinion this is racism. But Brazilian society and the federal government do not like to discuss racism."

Ms Malachias says there are three other black doctoral students in her school - but two are from Africa.

"Where are the black Brazilians?" she asks indignantly.

Growing movement

She says, however, that a growing black movement is now forcing politicians to take some notice.

And indeed politicians have been trying to woo the black vote.

But the inequalities of the rest of society are mirrored in the political system.

People living in slums may find it harder to organise to demand changes

Those campaigning for greater representation complain that only 2% of the present members of Congress are black and no top members of government are black.

At his close-of-campaign rally, workers' party candidate Luiz Inacio Lula da Silva - who is way ahead in the polls - introduced the African-American activist Jesse Jackson to the crowd.

Lula is promising to provide more jobs and education aimed at black Brazilians.

The government-backed candidate Jose Serra is also promising to expand the existing government's small affirmative action programme.

Voices of protest

In the slums and shanty towns surrounding Sao Paulo and other big cities, voices of protest are starting to be heard.

The Libertarios are a rap group, performing in the southern slums of Sao Paulo, whose music highlights the inequalities.

They have also set up a small community centre with a library and other facilities.

The community is very divided

Joselito Almeida, rap artist

They say one of the problems is that many Brazilians with both African and European forebears consider themselves to be white.

And the conditions of the slums generate divisions and apathy which make it hard to organise people to push for change.

"Many people, because they are unemployed, have become drug addicts," said the group's Joselito Almeida.

"The community is very divided. A lot of our generation went into drug gangs.

"Many of those that we grew up with were killed before they got to 20."

One of the Libertarios' songs describes the lack of opportunities for those growing up in the slums, the stereotyping of slum residents as ignorant, uneducated or criminal and asks whether slavery has really ended.

Given the potential size of the black vote in Brazil, it is surprising that the issue of race has not been more prominent in the elections.

It is a country only starting to recognise that it may have a problem with race equality.