Brazil's justice minister and prosecutors collaborated to convict left-wing icon Luiz Inacio Lula da Silva on corruption charges to prevent him from contesting the 2018 election, an investigative news outlet reported on Sunday.
Citing leaked documents, The Intercept website co-founded by Glenn Greenwald, said an anonymous source had provided material, including private chats, audio recordings, videos and photos that show "serious wrongdoing, unethical behavior, and systematic deceit".
Among the explosive claims, The Intercept said prosecutors in a massive, years-long anti-corruption probe known as "Car Wash" had expressed "serious doubts whether there was sufficient evidence to establish [former president] Lula's guilt".
Justice Minister Sergio Moro was the anti-corruption judge who handed Lula his first conviction in 2017, which prevented him from running in a presidential election he was widely expected to win.
President Jair Bolsonaro, who said during his campaign he hoped Lula would "rot in prison," later made Moro part of his cabinet.
Mr Greenwald, who was part of the team that first interviewed Edward Snowden in 2013, said on Twitter the leak was "one of the largest and most important in years".
This is "just the very beginning of what we intend to reveal from this massive archive about him [Mr Moro] and the prosecutors with whom he unethically worked," Mr Greenwald said.
The documents could not be verified by AFP.
The claims come at a bad time for Mr Bolsonaro who is already facing mounting opposition less than six months into his term. Latin America's biggest economy is teetering on the edge of recession and his signature pension reform remains stuck in a hostile Congress.
In response to The Intercept reports, Mr Moro defended his actions as judge in the ongoing Car Wash probe and said the material obtained through the "criminal invasion of prosecutors' cell phones" had been "taken out of context".
"Careful reading reveals that there is nothing there despite the sensational material," Mr Moro said.
The Car Wash task force confirmed its investigators had been hacked, but said it did not know the extent of the breach.
Lula, who led Brazil from 2003 to 2010, has denied all the corruption charges against him, arguing they were politically motivated to prevent him from competing in the elections.
He is serving a reduced jail term of eight years and 10 months after being convicted of accepting a seaside apartment as a bribe for helping the OAS construction company get lucrative deals with state oil firm Petrobras.
While behind bars, Lula's Workers' Party (PT) registered him as their presidential candidate in August 2018 – two months before the election. An electoral court barred him two weeks later.
A second conviction was handed down in February for which he was sentenced to almost 13 years.
Fernando Haddad, the PT's election candidate who lost to Bolsonaro, said on Twitter "we could be facing the biggest institutional scandal in the history of the republic".
"The truth will prevail" was posted on Lula's Twitter account above a link to The Intercept stories.
Days before filing the indictment that put Lula in jail, group chats involving prosecutors in the case show that chief prosecutor Deltan Dallagnol "expressed his increasing doubts over two key elements of the prosecution's case: whether the triplex was in fact Lula's and whether it had anything to do with Petrobras".
The leaked material also shows that "Car Wash prosecutors spoke openly of their desire to prevent the PT from winning the election and took steps to carry out that agenda," The Intercept said.
"Moro secretly and unethically collaborated with the Car Wash prosecutors to help design the case against Lula ... only for him to then pretend to be its neutral adjudicator."