Brazilian authorities have imposed round-the-clock police monitoring of former president Jair Bolsonaro amid warnings he represents a "concrete flight risk" ahead of his trial on coup-related charges that could result in a four-decade prison sentence.

Supreme Court Justice Alexandre de Moraes ordered discreet 24-hour surveillance of Bolsonaro's Brasília residence on August 26, instructing officers to maintain their presence without entering the property or disrupting the neighbourhood.

The enhanced security measures follow a request from the Attorney General's Office for "real-time monitoring of precautionary measures" after federal investigators uncovered evidence suggesting the 70-year-old had breached judicial restrictions whilst under house arrest.

Workers' Party representative Lindbergh Farias had petitioned for preventive detention, arguing that Bolsonaro had failed to adhere to court-imposed conditions, including prohibitions on social media activity and communicating with fellow defendants.

Federal authorities revealed they had uncovered a 33-page draft asylum request on Bolsonaro's mobile phone, addressed to Argentine President Javier Milei and dated February 2024. The document cited alleged "political persecution in Brazil" as justification for seeking international protection.

The discovery has intensified concerns about flight risk, particularly given the activities of Bolsonaro's son, Eduardo, who has been in the United States since February. Justice de Moraes noted that the congressman's "incessant actions" whilst abroad, including efforts to secure US sanctions against Brazilian judicial figures, had heightened fears his father might attempt to evade justice.

Eduardo Bolsonaro has publicly claimed credit for persuading US President Donald Trump to levy 50% tariffs on Brazilian exports in response to the legal proceedings against his father. The pressure campaign has resulted in Magnitsky sanctions being imposed on Justice de Moraes, measures typically reserved for serious human rights violators.

According to AFP, investigators allege Bolsonaro breached restrictions by maintaining contact with other defendants and sharing approximately 300 WhatsApp videos expressing support for co-accused – activities explicitly prohibited by the court.

The far-right leader faces charges of conspiracy, criminal organisation membership, and attempting to prevent President Luiz Inácio Lula da Silva from assuming office following the 2022 election, whose results are disputed by Bolsonaro. Prosecutors have recommended additional charges for allegedly obstructing the judicial investigation.

Supreme Court deliberations are scheduled to commence on September 2, with the trial expected to continue until September 12. Prosecutors must respond to defence arguments regarding alleged restriction violations by August 27.

President Lula weighed in on August 26, slamming Trump's intervention as behaving "as if he had been elected emperor of the world" and denouncing Eduardo Bolsonaro as a "traitor to the homeland".

Bolsonaro's legal team has rejected the accusations, characterising the police actions as attempts to "demoralise" their client. However, legal experts suggest the evidence makes conviction increasingly likely.

The former president has been wearing an electronic ankle monitor since mid-July and has been confined to his residence since early August. A parallel investigation is examining whether he and his son attempted to obstruct proceedings and pressure justices into dismissing the charges.