Bolsonaro is on trial at the Supreme Court for allegedly plotting to cling onto power after losing 2022 elections to President Luiz Inacio Lula da Silva. 

President Donald Trump has sought to punish Brazil, a longtime US ally, for what he sees as a politically motivated "witch hunt" targeting Bolsonaro by imposing eye-watering tariffs on Latin America's biggest economy.

The 70-year-old Bolsonaro is banned from social media for the duration of the proceedings, and third parties are barred from sharing his public remarks. 

But on Sunday, his allies defied the order by sharing footage online of a call between the former army captain and his eldest son Flavio at a solidarity rally in Rio de Janeiro.

Supreme Court Justice Alexandre de Moraes reacted furiously, declaring that the judiciary would not allow a defendant to "treat it like a fool" because of his "political and economic power."

Criticizing Bolsonaro's "repeated failure" to comply with the court's restrictions on him during the trial, he placed him under house arrest at his home in the capital Brasilia.

He also barred the country's former leader (2019-2022) from receiving visitors, apart from his lawyers, and from using mobile phones, and warned that any new transgression would lead to him being detained.

Several mobile phones were seized at his home on Monday, the police said.

Washington condemned the new restrictions on Monday night, with the State Department's Bureau of Western Hemisphere Affairs issuing a statement on X.

"Minister Alexandre de Moraes, already sanctioned by the United States for human rights violations, continues to use Brazilian institutions to silence the opposition and threaten democracy," the bureau posted. "Let Bolsonaro speak!"

US officials added that they would "hold accountable all those who collaborate with or facilitate sanctioned conduct."

The US post was re-shared by Bolsonaro's politician son Eduardo Bolsonaro, who had successfully lobbied Washington to take punitive action against Brazil over the case.

In a separate post, he wrote: "Brazil is no longer a democracy."

He called Moraes, who is presiding over Bolsonaro's trial and has styled himself a defender of Brazilian democracy in the face of the far right, an "out-of-control psychopath."

Last month, Moraes ordered Bolsonaro to wear an ankle bracelet and instituted the social media ban.

Trump responded in unprecedented fashion by banning Moraes from the United States and freezing his assets in US banks.

Trump's pressure campaign has angered many Brazilians but endeared him to Bolsonaro's conservative base.

At rallies in Rio, Brasilia and Sao Paulo on Sunday, some demonstrators waved US flags or held signs reading "Thank you Trump." 

Bolsonaro himself did not attend the rallies, having been ordered by the Supreme Court to stay home at night and at weekends throughout the trial.

Prosecutors say he and seven co-accused tried to overturn his 2022 election defeat in a plot that only failed because the military did not get on board.

He faces a 40-year sentence if convicted at the trial, which is expected to wrap up in the coming weeks.

Bolsonaro's supporters stormed Brazil's congress in January 2023, after Lula was inaugurated, ransacking the chambers and attacking police, in scenes reminiscent of an attack by Trump supporters on the US Capitol two years before.

Despite being barred from running, Bolsonaro hopes to mount a Trump-style comeback in Brazil's 2026 presidential election. 

Lula, 79, has said he may seek a fourth term, health permitting. 

Last year, he was hospitalized for a brain hemorrhage caused by a bathroom fall.