Brazilian police on Tuesday arrested four soldiers guarding the G20 summit over an alleged plot to assassinate then President-elect Luiz Inacio Lula da Silva in a 2022 "coup," a federal police source told AFP.
The four "were arrested in Rio, where they were participating in the security operation for the G20 leaders' meeting," said the source, who added that a police officer was also taken into custody.
A statement by Brazil's federal police said the suspects were "mostly soldiers with special forces training," but made no mention of them being part of the G20 summit security deployment.
They were arrested on the second day of the G20 gathering, in an operation to "dismantle a criminal organization responsible for planning a coup d'etat to prevent the government legitimately elected in 2022 elections taking office," the police said.
US President Joe Biden and his Chinese counterpart Xi Jinping are among leaders in Rio for the annual get-together of the heads of the world's biggest economies.
Security is tight for the event, with troops in armored vehicles lining the streets of the usually laid-back seaside city.
Tuesday's arrests come under a week after a failed bomb attack on the Supreme Court by a suspected far-right extremist, who killed himself in the process.
The alleged plot against Lula was to have been carried out on December 15, 2022 -- just weeks before the veteran leftist returned to office at the start of 2023 -- and involved "the murder of the candidates to the presidency and vice presidency," the statement said.
The suspected coup-plotters, who also planned to assassinate a Supreme Court justice, intended afterwards to set up a "crisis cabinet" with themselves in it, the police added.
Brazilian media said the judge they plotted to kill was Alexandre de Moraes, a powerful justice who has drawn the ire of the right for his investigations into the far-right and for shutting down the social network X for 40 days in a fight with its owner Elon Musk over disinformation.
The suspects possessed "advanced military operational" know-how and had codenamed their plot "Green and Yellow Dagger," according to the authorities, in apparent reference to colors on the Brazilian flag.
They face potential charges of violently trying to overthrow the government, coup-plotting and being part of a criminal organization, the statement added.
In October 2022, Lula defeated far-right incumbent Jair Bolsonaro, who had served a single term in office, to regain power after a decade's absence.
Thousands of Bolsonaro supporters stormed government buildings in Brasilia on January 8, 2023 in an insurrection reminiscent of the 2021 storming of the US Capitol by supporters of Donald Trump.
Several investigations have been opened into the Brasilia riots, as well as other alleged plots to prevent Lula taking office.
The man who carried out a failed bomb attack on the Supreme Court last week, killing himself in the process, is also suspected of involvement in the 2023 unrest.
