RIO DE JANEIRO, April 21, 2024 (BSS/AFP) - Brazil's former president Jair Bolsonaro is set to rally supporters in Rio de Janeiro on Sunday in defense of freedom of expression, which he says is under threat in the country, as tech tycoon Elon Musk faces a legal showdown there over claims of censorship and disinformation.

The rally is planned for 10:00 am (1300 GMT) Sunday at Rio's famed Copacabana beach.

"The whole world is aware of how threatened our freedom of expression is," the 69-year-old far-right leader said in a video posted Thursday on his social media accounts.

"Let's do our peaceful act, in defense of democracy, for our freedom, without signs or banners," he added.

Brazilian authorities are investigating whether Bolsonaro plotted an attempted coup to prevent his 2022 election opponent and current President Luiz Inacio Lula da Silva from assuming office in January 2023.

Bolsonaro has already been barred from public office for eight years for baselessly trashing Brazil's voting system ahead of the 2022 poll.

Last month, federal police also recommended he be charged for falsifying his Covid-19 vaccination records. He has denied all charges against him.

Musk, the billionaire owner of social media platform X, is also under investigation in Brazil after he accused a Supreme Court justice this month of censoring social networks, calling him a "dictator" and vowing to disobey rulings to block users found to be spreading disinformation.

The judge, Alexandre de Moraes, has waged a crusade against disinformation, especially attempts by far-right supporters of Bolsonaro to discredit Brazil's voting system.

Users blocked by Moraes include figures like far-right ex-congressman Daniel Silveira, who was sentenced to nine years in prison in 2022 on charges of leading a movement to overthrow the Supreme Court.

Musk had vowed to reinstate blocked accounts, saying: "We will probably lose all revenue in Brazil and have to shut down our office there" but "principles matter more than profit."

He has not followed through on his threats, however, and the Brazilian office of X has said it will comply with court orders to block users spreading disinformation.

Moraes has responded to Musk's attacks by ordering fines of 100,000 reais (around $20,000) a day for any blocked account that X reactivates.

Accusing Musk of "criminal instrumentalization" of the platform, Moraes also placed the Tesla and SpaceX boss under investigation for crimes including conspiracy and obstruction of justice.

Brazil is part of a growing international debate about the limits of free speech on social media, where some say allowing a free-for-all endangers democracy.

Bolsonaro's Rio rally planned for Sunday follows a Sao Paulo gathering of his supporters in February that researchers said attracted around 185,000 people.