Supporters of Brazilian leftist icon Luiz Inacio Lula da Silva gathered outside a prison Friday waiting for the ex-president's release following a court ruling that threatens to deepen political divisions.

Lula is among several thousand convicts who could be freed after the Supreme Court's decision late Thursday to overturn a rule requiring convicted criminals to go to jail after losing their first appeal.

They would remain free until they had exhausted their rights to appeal their conviction -- 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.

Dozens of people yelling "good morning, Lula" and waving "Free Lula" signs stood outside the federal police headquarters in the southern city of Curitiba on Friday where the former president has been held since April 2018.

They hope Lula will "leave the room where he has been kidnapped for 580 days, walk among the people and come to the vigil, hug the people, and we hug him, to share this special moment that is the conquest of his liberty," Roberto Baggio, coordinator of the Free Lula camp outside the jail, told AFP.

- A hero to millions -

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, is 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.

Lula's lawyers said they would seek the "immediate release" of the 74-year-old leftist leader, who remains an extremely popular, albeit divisive, figure in Brazil.

A judge needs to authorize his release, which could be as early as Friday.

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

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

But his release could simultaneously invigorate the left and 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.