A Supreme Court judge in Brazil has suspended former president Luiz Inacio Lula da Silva's appointment to a cabinet post amid a corruption probe, calling it a clear attempt to help him get around his legal woes.
Brazil faces a serious political crisis and massive protests over President Dilma Rousseff's administration's attempt to appoint Lula as chief of staff.
Justice Gilmar Mendes said on Friday that Rousseff's decision to employ Lula was a "clear" attempt to prevent him from being arrested on corruption charges.
"The goal of the falsity is clear: prevent the carrying out of preventive arrest order" against Lula being considered by a lower court, Mendes wrote in her ruling.
The judge's decision was expected to stoke already high tensions and came shortly after tens of thousands of supporters of Brazil's center-left government rallied to back Lula and his successor, Rousseff.
Anti-government protests over the weekend brought an estimated three million people on to the streets in nationwide.
'Petrobas kickback scheme'
Two weeks ago, Lula was brought in for questioning in a sprawling investigation into an alleged kickback scheme in the state oil company Petrobras. If he becomes a cabinet minister, he can only be prosecuted with the approval of the Supreme Court.
Mendes' decision leaves Lula, and Latin America's largest nation, in limbo. The government is expected to appeal against the decision, which will eventually have to be decided by the full court.
However, with Holy Week next week, it could be some time before the full court meets.
Earlier on Friday, an appeals court slapped down a separate attempt to keep Lula from returning to the government while tens of thousands of his supporters rallied to back an embattled government facing a host of crises.
Lula was sworn in as chief aide to Rousseff on Thursday, a post that will let the politician help the president battle an impeachment effort and one that also makes it harder to investigate any possible links to a corruption scandal at the state oil company.
Tens of thousands of supporters of Lula, who was one of the world's most famous leaders as president from 2003 to 2010, gathered in rallies across Brazil, particularly in the industrial south, where the former factory worker has his base. Many wore red T-shirts and caps and frequently chanted, "Lula, the minister of hope".
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While Rousseff's opponents accuse her of trying to help Lula avoid legal woes, her supporters have a different take.
They say the 70-year-old Lula, known for his ability to build consensus, could save Rousseff's job and help bring the economy back from the abyss.
Rousseff, with approval ratings in the single digits, is fighting against attempts to remove her over allegations of fiscal mismanagement unrelated to the Petrobras case.
The move towards impeachment advanced this week as the lower house established a special commission on the matter.
Both Rousseff and Lula have repeatedly denied any wrongdoing.