Former Brazilian President Jair Bolsonaro on Sunday told a judge that medicine-induced paranoia and hallucination caused him to tamper with an electronic ankle monitor, court records showed, a day after police took him into custody out of fear he might flee.

Supreme Court Justice Alexandre de Moraes ordered Bolsonaro's detention on Saturday, after more than 100 days of house arrest, citing potential flight risk as the right-wing leader awaits final appeals of his prison sentence for plotting a coup.

In a 30-minute custody hearing on Sunday, Bolsonaro denied any intent to escape or try to remove the ankle monitor.

He attributed his behaviour to a mix of anticonvulsant drugs prescribed by different doctors for his chronic hiccups, which led him to imagine there was listening equipment inside the tracking device.

The 70-year-old former president said he was alone during the episode, as the others in his home at the time – his daughter, his older brother and an adviser – were sleeping.

"The witness stated that, around midnight, he tampered with the ankle bracelet, then 'came to his senses' and stopped using the soldering iron, at which point he informed the officers guarding him," according to the court document seen by Reuters.

The judge overseeing Sunday's hearing decided to keep Bolsonaro in police custody, concluding that the officers had followed all applicable laws during the arrest.

Bolsonaro is being held in a 12-square-metre cell at federal police headquarters in Brasilia, with a bed, TV, air conditioning and private bathroom. A panel of Supreme Court judges will convene on Monday to consider his case.

His lawyers on Sunday repeated their request for the right-wing former army captain to be kept under "humanitarian house arrest."

US President Donald Trump, who had called Bolsonaro's trial a witch hunt and imposed an extra 40 percent tariff on many Brazilian goods to counter it, began partially walking that policy back on Thursday, with exemptions for imports of beef, coffee, cocoa and fruits.

On Saturday, Trump told reporters he had been unaware of Bolsonaro's detention. "Is that what happened? That's too bad," he said. He also said he would be meeting again soon with President Luiz Inacio Lula da Silva, Bolsonaro's leftist successor.

State Department officials expressed concern about the treatment of Bolsonaro, calling it an attack on the rule of law and political stability.

Brazil's top court sentenced Bolsonaro in September to 27 years and three months in prison for plotting a coup to overturn the 2022 election, which he lost to Lula.

Bolsonaro's lawyers have been hoping to convert his sentence into a long-term house arrest due to chronic health issues.

The former president, who was stabbed in the abdomen during a 2018 campaign event, has a history of hospitalisations and surgeries related to the attack.

"What the case files and the events of the early hours of November 22 show is the extremely delicate state of the former president's health, exactly as described in the medical reports and examinations already included in the files," Bolsonaro's lawyers wrote in a Sunday court filing.

They said events that night were caused by his "illogical behaviour" due to an unfortunate combination of medication, age and stress, and that there was no risk of him fleeing. (Reuters)