Brazil's ex-president Jair Bolsonaro takes his legal woes to the street on Sunday, calling for a mass protest from supporters amid accusations he plotted a coup to stay in power.

The 68-year-old former army officer has urged his backers to attend a "peaceful rally in defense of the democratic rule of law" in the economic capital Sao Paulo which organizers hope will draw at least 500,000 people.

Bolsonaro has had his passport seized by police as he and his inner circle face scrutiny over plans to try to remain in power after he lost 2022 elections to President Luiz Inacio Lula da Silva.

The far-right former president Bolsonaro has denied the accusations and he refused to answer questions during a half-hour interrogation Thursday at federal police headquarters in Brasilia.

"No one attempted a coup in Brazil. That is the great truth," Bolsonaro told radio station CBN Recife.

A week after Lula took office on January 1, 2023, thousands of Bolsonaro supporters stormed the presidential palace, Congress and Supreme Court, urging the military to intervene to overturn what they called a stolen election.

Bolsonaro, who was in the United States at the time, denies responsibility, and has even suggested the protesters were not really his supporters.

However, investigators allege months of anti-democratic maneuvers by Bolsonaro, from a plan to discredit Brazil's electronic voting system with a "disinformation" campaign ahead of the elections to "legitimize a military intervention" if he lost.

Police say Bolsonaro edited a draft presidential decree that would have declared a state of emergency, called new elections and ordered the arrest of Supreme Court Justice Alexandre de Moraes, the head of Brazil's Superior Electoral Tribunal.

They also released a video of a July 2022 meeting where a shouting, swearing Bolsonaro ordered cabinet ministers to help him discredit the election system.

Test of support

Bolsonaro, who led Brazil from 2019 to 2022, claims to be the victim of "persecution."

He is facing several other investigations, such as the falsification of Covid-19 vaccination certificates, or the alleged misappropriation of gifts received from other nations, such as jewelry offered by Saudi Arabia.

In June, the electoral tribunal barred Bolsonaro from running for office until 2030 over his attacks on the election system.

Nevertheless, Bolsonaro is still considered the leader of the opposition and is adored by his fervent supporters.

The protest on Sunday afternoon is seen as a litmus test of his support ahead of October municipal elections, in which his influence is expected to play a key role in the still-polarized nation.

"If there is a lot of support, he will be able to say that the people are with him. Otherwise, he will lose all legitimacy," Andre Rosa, a political scientist at the University of Brasilia, told AFP. 

Sao Paulo Governor Tarcisio de Freitas, a former minister in Bolsonaro's government, and the city's mayor, Ricardo Nunes, are among the officials expected to attend.

One of Bolsonaro's lawyers, Fabio Wajngarten, said Thursday that he hoped to see "500,000 to 700,000" demonstrators.

Bolsonaro urged his supporters to come dressed in the yellow and green of Brazil's flag, which he claimed as a symbol when in office.

"I'm going there, for Brazil. It will be gigantic!" a lawmaker from Bolsonaro's party, Bia Kicis, wrote on X.