Jair Bolsonaro has been taken into custody after being determined a 'concrete flight risk' while under house arrest.
The right-wing former Brazilian president was found guilty of plotting a military coup in September and sentenced to more than 27 years in prison, but he remains under house arrest pending appeals.
Brazilian Supreme Court Justice Alexandre de Moraes said the move to detain the 70-year-old was a preventative measure after 'new facts' came to light.
Bolsonaro admitted he had tried to open his ankle monitor with a soldering iron - but denied he wanted to remove it. Court officials said he wanted to use a planned rally outside his house as a cover to break free.
In a filing authorizing the arrest, Justice Moraes said information from the center monitoring Bolsonaro's house arrest suggested the former president's 'intention to break the electronic ankle bracelet to ensure success in his escape'.
This, it said, would be 'facilitated by the confusion caused by the demonstration called by his son'.
Flávio Bolsonaro, who serves as a senator, called for a gathering of his supporters near his father's home to take place on Saturday night. He wrote on social media, 'Are you going to fight for your country, or watch it all from your phone there on your sofa? I invite you to fight with us.'
To explain his decision, Justice Moraes cited the possibility of Bolsonaro fleeing to foreign embassies, citing 'a history of planning to request asylum through a diplomatic representation'.
The court filing notes that the US embassy in the capital, Brasilia, is located about 13km (8 miles) from Bolsonaro's home.
Bolsonaro's legal woes have drawn the ire of fellow right-wing populist US President Donald Trump, prompting him to impose a 50% tariff on imports of Brazilian goods.
Bolsonaro is being held in a police station in Brasilia and will undergo a custody hearing on Sunday.
It was only on Friday that the former president's lawyers asked the Supreme Court to allow him to serve his whole jail sentence under house arrest, with electronic monitoring. They also asked that Bolsonaro be allowed to leave his home for medical treatment, saying he required regular treatment for pulmonary infections and other ailments.
Bolsonaro was found guilty of leading a conspiracy aimed at keeping him in power after he lost the 2022 election to his left-wing rival, Luiz Inácio Lula da Silva.
Supreme Court justices stated that he knew of a plot which included plans to assassinate Lula and his vice-presidential running mate, Geraldo Alckmin, and to arrest and execute Moraes - who has been overseeing Bolsonaro's trial.
The conspiracy failed to gain the backing of army and air force commanders. Lula was sworn in without incident on 1 January 2023. However, a week later, on 8 January, thousands of Bolsonaro supporters stormed government buildings in Brasília, leading to security forces intervening and approximately 1,500 arrests.
The justices found that the rioters had been incited by Bolsonaro, whose plan was for the military to step in and return him to power.
