Brazil's left-wing leader Luiz Inacio Lula da Silva returned to his trade union stronghold on Saturday, delivering a fiery speech to throngs of celebrating supporters a day after walking free from jail.

Reveling in the adoration of his followers at the metalworkers' union he once led, Lula attacked his arch-nemesis President Jair Bolsonaro, who hours earlier had called him a "scoundrel," and those who jailed him last year for corruption.

"He (Bolsonaro) was elected to govern for the Brazilian people and not to govern for the militias in Rio de Janeiro," said Lula, his face flushed as he ranted for nearly an hour in the heat.

Former Brazilian President Luiz Inacio Lula da Silva gestures as he leaves the Federal Police Headquarters, where he was serving a sentence for corruption and money laundering, in Curitiba, Parana State, Brazil, on November 8, 2019 Former Brazilian President Luiz Inacio Lula da Silva gestures as he leaves the Federal Police Headquarters, where he was serving a sentence for corruption and money laundering, in Curitiba, Parana State, Brazil, on November 8, 2019 Photo: AFP / HENRY MILLEO

Lula was mobbed when he arrived at the union in Sao Bernardo do Campo, near Brazil's biggest city of Sao Paulo, as people jostled to hug and shake hands with the former shoeshine boy who rose to become one of Brazil's most popular presidents.

The compound was decorated with a huge banner of Lula's image and surrounded by a sea of supporters wearing red T-shirts and waving "Free Lula" flags.

"I am grateful that they released him from an unjust imprisonment, from a fraud," Roque Enrique, 24, told AFP as she stood for hours waiting for Lula to arrive.

Lula in prison Lula in prison Photo: AFP / Gal ROMA

Tamara Blanco, 38, said Lula was the "best president Brazil has had... I always believed he would get out (of jail)."

Lula's release came after a politically sensitive Supreme Court ruling on Thursday that could free thousands of convicts.

A 6-5 decision overturned a rule requiring convicted criminals to go to jail after losing their first appeal.

People gather outside of a police station in Curitiba, where former president Luiz Inacio Lula da Silva is detained, waiting for his release, after the Brazil's Supreme Court issued a ruling that could free him People gather outside of a police station in Curitiba, where former president Luiz Inacio Lula da Silva is detained, waiting for his release, after the Brazil's Supreme Court issued a ruling that could free him Photo: AFPTV / Florian PLAUCHEUR

Those convicts would remain free until they had exhausted their rights to appeal -- a process critics say could take years in cases involving people able to afford expensive lawyers.

Bolsonaro, who said on last year's election campaign trail that he hoped Lula would "rot in prison," told his Twitter followers Saturday that Lula was "momentarily free, but guilty."

The Supreme Court's decision and Lula's release provoked thousands of pro-government protesters to take to the streets in Rio de Janeiro and Sao Paulo on Saturday in opposition of the court's ruling.

Former Brazilian President Luiz Inacio Lula da Silva embraces a woman as he leaves prison Former Brazilian President Luiz Inacio Lula da Silva embraces a woman as he leaves prison Photo: AFP / CARL DE SOUZA

Lula's criminal record prevents him from running for political office, at least for now.

Lula speaks at the rally in in Sao Bernardo do Campo, Brazil, on November 9, 2019 Lula speaks at the rally in in Sao Bernardo do Campo, Brazil, on November 9, 2019 Photo: AFP / NELSON ALMEIDA

But his freedom is likely to reinvigorate the rudderless left that has floundered since the charismatic 74-year-old was jailed in April 2018.

It also threatens to deepen political divisions in the country as the tough-talking Bolsonaro, who was swept to power last year on a wave of anti-left sentiment, goes on the offensive.

The court decision undermines a sprawling corruption investigation called Car Wash that has put dozens of political and business leaders behind bars, including Lula -- a probe supported by many ordinary Brazilians fed up with white-collar crime.

In an impassioned address on Friday to hundreds of supporters who greeted him as he walked out of the federal police headquarters in the southern city of Curitiba, Lula vowed to keep fighting for poor people.

Supporters listen to Lula's address at a rally on November 9, 2019 Supporters listen to Lula's address at a rally on November 9, 2019 Photo: AFP / NELSON ALMEIDA

The former trade union leader who helped found the Workers Party (PT) denounced the economic policies of Bolsonaro.

"People are hungrier, they have no jobs, people work for Uber or delivering pizzas on a bike," Lula said in remarks sometimes drowned out by cheers from the crowd and fireworks overhead.

Lula led Brazil through a historic boom from 2003 to 2010, earning the gratitude of millions of Brazilians for redistributing wealth to haul them out of poverty.

He was serving eight years and 10 months for corruption and money laundering. He was sentenced to almost 13 years in February in a separate corruption case and still faces another half dozen corruption trials.

Lula has denied all the charges, arguing they were politically motivated to keep him out of the 2018 presidential election that he was tipped to win.

Justice Minister Sergio Moro, who convicted Lula when he was a judge in 2017, said Saturday that while the Supreme Court's decision must be respected, it could be "altered... by Congress" to allow the jailing of convicted criminals after their first appeal.

"I am back," Lula declared Saturday in his speech, calling Moro "not a judge, but a villain."

Moro, who joined Bolsonaro's cabinet in January, has faced calls for his resignation over leaked chats purportedly showing he worked with Car Wash prosecutors to keep Lula out of last year's presidential race.

Moro has denied wrongdoing and accused criminals of hacking the messages with the aim of overturning convictions resulting from the investigation.

Lula's political prospects could change if the Supreme Court were to decide in a separate case that Moro had been biased.

Despite his age, Lula made clear he is not going to sit on the sidelines.

"I'm a very young man. I am 74 from a biological point of view, but I have the energy of a 30-year-old," he said in a video posted on his official Twitter account Saturday.

That followed a video Friday showing Lula working out in the prison gym, lifting weights and running on a treadmill, to Survivor's classic hit "Eye of the Tiger."

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