Brazil’s capital is preparing for the possibility of more violent demonstrations by people seeking to overturn the presidential election.

Local security officials on Wednesday (today NZ time) blocked access to buildings trashed four days earlier by a horde of rioters.

A flyer promoting a “mega-protest to retake power” circulated on social media platforms, particularly Telegram, and urged protesters to turn out in two dozen cities, including the capital.

It was unclear how large or violent such demonstrations might shape up to be, but skittish authorities took no chances.

Speaking to journalists in Brasilia, the federal appointee who has assumed control of the capital’s security said police were shutting down the main avenue to traffic and limiting pedestrian access with barricades. They were blocking all access to the square that was the site of Sunday’s mayhem, said the official, Ricarado Cappelli.

He said a small area on the avenue had been reserved for peaceful demonstrations, but would be surrounded by police and the national guard and all protesters searched upon entry.

A forensic investigator stands outside the Brazilian Supreme Court building in front of windows damaged by supporters of Brazil's former President Jair Bolsonaro, in Brasilia, Brazil. Photo / AP

“The right to protest freely will always be respected and cannot be confused with terrorism,” Cappelli said.

Citing the call to action on social media, a Supreme Court justice ordered local authorities in cities across Brazil to prevent protesters from blocking roads or occupying public spaces and buildings. Justice Alexandre de Moraes also ordered arrests and fines for people and companies who participate or help with logistics and funding.

The nation remains on edge after supporters of former President Jair Bolsonaro rampaged through Congress, the Supreme Court and the presidential palace on Sunday, laying ruin to the government’s three most important buildings. Officials arrested or detained some 1500 people by the following morning, hundreds of whom were sent to prison.

Though there is no evidence of fraud in the October 30 presidential election, the protesters have claimed the true winner was far-right Bolsonaro. He has fired up his base about the vulnerability of electronic voting machines despite independent experts’ assurances they are closely scrutinised. Bolsonaro also has warned his supporters that the election’s leftist victor, Luiz Inácio Lula da Silva, would impose communism.

The fresh call for an uprising has sparked concern that the crackdown hasn’t damped the will of radicals.

Among those who vow to continue struggling is Daniel Bressan, 35, who travelled some 300 miles (480km) from the interior of Parana state to join Sunday’s protest in Brasilia. He was detained by police the next morning, though he denies participating in any of the vandalism.

Protesters, supporters of Brazil's former President Jair Bolsonaro, attack police armoured vehicles as they storm the Planalto Palace in Brasilia, Brazil. Photo / AP

“A lot of people are going to be afraid to go to the streets and be arrested — I myself fear persecution by the legal system — but I’m not going to stop fighting and I’m not going to get discouraged,” Bressan said by phone from the federal police’s temporary holding centre. “I’m ready for everything. Our freedom is worth more than our lives.”

Jailing rioters represent only part of the government’s effort to hold people responsible. Authorities also seek to track down those who enabled the uprising. That includes organiSers who summoned protesters to the capital and paid their way as well as local security personnel accused of either standing by and allowing the destruction to occur, or even cooperating.

Justice Minister Flávio Dino told local press this week authorities have identified some of the protest’s financiers. He said they are based in the south and centre-west regions that Bolsonaro carried in the election. Without identifying individuals, he said they are members of the agribusiness sector, local business owners and people registered to own firearms.

Dino previously said the riot was apparently intended to spark a domino effect around the country. He has referred to the encampments that had been set up by Bolsonaro supporters outside military buildings to call on the armed forces to overturn election results as “incubators of terrorists”. Authorities cleared away the camps in Brasilia and other cities after the rioting.

In November, the Supreme Court froze 43 bank accounts of people accused of having financed roadblocks that disrupted highway traffic in the wake of Lula’s victory. At least 30 were in the centre-west state of Mato Grosso, Brazil’s top soybean producer.

De Moraes, the Supreme Court justice, also ordered preventative detention for the men who were serving on Sunday as head of the federal district’s security and military police chief, as well as searches of their residences. Both men have been fired since the rioting.

 “Absolutely NOTHING justifies the omission and collusion of the security secretary and the military police commander,” de Moraes wrote in his decision, which was made public late on Tuesday.

The justice also denounced the protest encampments sponsored by diverse financiers.

“There are strong indications that the conduct of criminal terrorists could only have occurred with the willful participation or omission — which will be determined in these investigations — of the aforementioned public authorities,” de Moraes wrote.

The fired security secretary, Anderson Torres, had been Bolsonaro’s justice minister. Cappelli, the federal appointee who now controls the secretariat, said on Wednesday that Torres assumed his new position, immediately fired subordinates and then travelled to Florida.

Cappelli previously told local media there were signs Torres’ actions amounted to intentional sabotage of security ahead of Sunday’s violence.

Torres said on Tuesday night on Twitter that he was interrupting his vacation and returning to Brazil to present his defence. He said ethics and legality had always governed his actions.

- Carla Bridi and Natalia Scarabotto, AP