(Mariella Franco/Facebook)

Protests have been held across Brazil after councillor and activist Marielle Franco and her driver were shot dead in a suspected assassination.

Franco, 38, was an openly serving lesbian politician who fought for minorities across Rio de Janeiro, where she grew up in one of the many favelas.

She won the fifth-highest vote count of council members in 2015, defying the odds which were set against her as a black, gay woman.

She often spoke openly about the need to crack down on discrimination against minority groups, as well as police violence who she said exercised excessive force.

Police officials confirmed that two men in a car fired nine shots at Franco and her driver, Anderson Pedro Gomes, 39, on Wednesday.

A press officer was also travelling with Franco and Gomes, but survived the shooting.

Officials have confirmed that it appears Franco was specifically targeted and not shot in a random attack.

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A “full investigation” is going to be carried out over the death, confirmed the head of public security Richard Nunes.

Following the attack, thousands took to the streets outside of Rio de Janeiro’s council chamber to protest against the growing violence in Brazil.

Crowds chanted “not one step backwards” as Franco’s coffin was carried inside.

Franco’s murder has been condemned worldwide by leading human rights charities.

The Human Rights Watch has called for a full independent investigation to be carried out.

Maria Laura Canineu, Brazil director at Human Rights Watch, said that she was an “outspoken and courageous advocate for victims of police abuse and a tireless defender of the rights of women and Afro-Brazilians.

“Brazilian authorities need to respond decisively by identifying those responsible for the killing of Marielle and Anderson, and bringing them to justice,” Canineu added.

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In February, Brazil President Michel Temer put the military in charge of security in Rio in an attempt to crackdown on the growing number of violent crimes in the city.

Canineu said that the “climate of near total impunity in Rio de Janeiro needs to end once and for all.

“Marielle and Anderson are the latest victims of a security system that has long failed to stop violence, or to ensure justice for the victims.”

Friends, family and fans of Franco have shared their memories of the activist.

In a statement, Brazil’s former president Dilma Rousseff called Franco as a “tireless social warrior”.

“Sad days for a country where a human rights defender is brutally murdered,” she said.

Franco’s murder was described as “an irreparable loss” by Redes da Maré, a non-profit group based in the favela where she grew up.

Jefferson Barbosa, 21, worked with Franco at the state legislature.

The communications student said she “was a symbol of the politics we believe in” but he was “scared” that this had happened.

“People are shocked with what happened. They did this to Mari, one of the most popular lawmakers in Rio. What will stop them doing this to others?” Barbosa added.