Brazil's Supreme Court Chief Justice Edson Fachin acted on September 9 to contain an unprecedented power struggle within the country's highest court, suspending a series of conflicting rulings issued by fellow justices less than a month before Brazilians go to the polls to elect a new president and most of Congress.

The clash, triggered by an investigation into a massive banking fraud scheme, has plunged the court into its biggest crisis since Brazil's return to democracy more than four decades ago.

Fachin annulled the effects of rival decisions issued by two of his colleagues and called an extraordinary session of the full court for next week to resolve the dispute, Reuters reported, citing a summary of the ruling.

At the centre of the row is the leadership of Brazil's Federal Police. Justice André Mendonça, a former justice minister under ex-president Jair Bolsonaro, ordered the preventive suspension of federal police director Andrei Rodrigues on September 8, accusing the force of illegally spying on him.

Justice Flávio Dino swiftly reversed that decision and reinstated Rodrigues, who returned to his post the following day, according to AFP, which cited the federal police press office.

Fachin's ruling effectively keeps Rodrigues in his job for now, while reserving a final decision pending further information to be provided within 48 hours.

Fachin also ordered the suspension of all proceedings related to an investigation into members of the court itself.

The dispute erupted last week after the publication of a police report revealing messages sent from banker Daniel Vorcaro to a number attributed to Justice Alexandre de Moraes.

Vorcaro, a well-connected banker who was arrested in November over suspicions of multibillion-dollar financial embezzlement that led to the liquidation of his bank, Banco Master, allegedly asked for help evading the investigation and delaying police operations against him.

Moraes, who led the high-profile trial that last year saw Jair Bolsonaro jailed over a 2022 coup attempt following his election defeat, denied any contact with the former banker and responded by asking that Mendonça be investigated for abuse of authority, citing a police intelligence report.

Mendonça, who ordered the disclosure of Vorcaro's messages and sought to determine whether Moraes was their intended recipient, in turn accused the federal police of illegal espionage against him and ordered Rodrigues's suspension – the move Fachin has now suspended pending next week's plenary session, scheduled for September 15.

Meanwhile, President Luiz Inácio Lula da Silva called on the Supreme Court to lift the judicial secrecy surrounding the wider Banco Master fraud investigation, which he described as "the biggest financial crime in Brazil's history."

In a message posted on social media, Lula said it was "urgent" to gain access to the investigations into everyone involved, "whoever they are and no matter who it hurts."

"Given the gravity of the biggest financial crime in Brazil's history, the Brazilian people need explanations and immediate measures to address the institutional crisis that has gripped the judiciary," Lula said.

He also criticised what he called "selective leaks" about the case, which he said were affecting the presidential campaign.

The crisis comes weeks before Lula seeks re-election in October against right-wing rival Flávio Bolsonaro, son of the jailed former president.

Flávio Bolsonaro has described the turmoil within the court as "chaos left behind by Lula."

However, he has also been pulled into a separate scandal surrounding the disgraced bank. Messages leaked to Brazilian outlet The Intercept in May showed the senator negotiated directly with Vorcaro over funding for an international film about his father's life, with about $21mn earmarked for the project. Flávio Bolsonaro has denied any financial ties between his family and Banco Master, calling such claims a "false narrative" created by Lula.

Several right-wing presidential hopefuls, meanwhile, have seized on the court's internal disputes to demand the removal of Moraes, who is seen as close to the president.

Fachin's extraordinary session next week is expected to determine how the court proceeds with both the police leadership dispute and the broader fallout from the Banco Master case, which has drawn in some of Brazil's most senior judicial figures just as the country heads into a tightly contested election.