Brazil's leftist icon Luiz Inacio Lula da Silva walked free from jail Friday after a year and a half behind bars for corruption following a court ruling that could release thousands of convicts.

The former president, wearing a black T-shirt and suit jacket, pumped his fist in the air as he exited the federal police headquarters in the southern city of Curitiba and was quickly mobbed by hundreds of supporters and journalists.

In an impassioned address, Lula vowed to "continue fighting" for ordinary Brazilians and expose the "lying side of the federal police." His croaky voice was at times drowned out by the cheers of the crowd and by fireworks.

"I didn't think that today I could be here talking to men and women that during 580 days shouted good morning, good afternoon or goodnight, no matter if it was raining or 40 degrees (Celsius)," he said, flanked by his girlfriend Rosangela da Silva, whom he kissed on stage.

"Now I'm going to Sao Paulo and afterward the doors of Brazil will be open so that I can travel around this country."

Lula's highly anticipated exit from the facility where he had been held since April 2018 came hours after his lawyers requested the immediate release of the 74-year-old, who has been serving a nearly nine-year sentence for corruption and money laundering.

Late Thursday, the Supreme Court overturned a rule requiring convicted criminals to go to jail after losing their first appeal. Lula is one of several thousand convicts who could benefit from the decision.

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.

Many of those affected by the 6-5 ruling are political and business leaders caught up in a massive corruption probe dubbed Car Wash that began in 2014.

Lula was "very serene" and the Supreme Court ruling had given him "hope that there could be justice," his lawyer Cristiano Zanin said earlier.

"Our judicial battle continues, our focus is to get the legal case nullified."

Lula, who led Brazil through a historic boom from 2003 to 2010, earning him the gratitude of millions of Brazilians for redistributing wealth to haul them out of poverty, was serving eight years and 10 months for corruption.

He was sentenced to almost 13 years in jail 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 was won by far-right President Jair Bolsonaro.

"I'm coming for you, wait for me!" da Silva, Lula's girlfriend, tweeted after the Supreme Court announced its decision.

"If all the others did worse and are free, why not him too?" Eleonora Cintra, a 74-year-old resident of Sao Paulo, told AFP.

Bolsonaro has been unusually quiet about the court's ruling that freed his nemesis. But his sons have taken to Twitter to attack the decision.

"Thousands of prisoners will be released and rattle everyone, regardless of their political beliefs, generating serious internal and external social and economic reactions," Carlos Bolsonaro tweeted.

Justice Minister Sergio Moro, who convicted Lula when he was a judge in 2017, said the Supreme Court's decision must be respected, but he noted "Congress can modify the Constitution or the law" to allow the jailing of convicted criminals after their first appeal.

In Caracas, leftist President Nicolas Maduro hailed Lula's release, saying "the Venezuelan people are happy and welcome Lula's freedom." And in the US, liberal presidential hopeful Bernie Sanders said that in Brazil no one had done more than Lula to reduce poverty and defend workers.

"I am delighted that he has been released from jail, something that never should have happened in the first place," Sanders tweeted.

Even though he has been freed, Lula's criminal record will prevent him from resuming his political career. He was the founder of the Workers Party (PT).

That could change, however, if the Supreme Court were to decide in a separate case that Moro had been biased.

Lula's release could invigorate the left and, paradoxically, also help Bolsonaro, who was swept to power in 2018 on a wave of anti-PT sentiment, said Thomaz Favaro of Control Risks consultancy.

"You will have Lula more present on the political scene and that allows Bolsonaro to reinforce his role as leader of the anti-PT field," Favaro said.

Lula will spend his first day of freedom visiting the metalworkers' union he once led near Sao Paulo, Brazil's biggest city.