The world's richest man and one of Brazil's Supreme Court judges are set for a showdown with Elon Musk's social media platform X, which faces a ban in the world's fourth-largest economy.

Supreme Court judge Alexandre de Moraes issued an order on Wednesday that X appoint a new legal representative within 24 hours or face closure.

In Wednesday's decision, Moraes says that under the country's law governing Internet matters, companies that do not comply with Brazilian legislation or the confidentiality of private information can have their activities temporarily suspended.

X's refusal to appoint a legal representative would be particularly problematic ahead of Brazil's October municipal elections, with a wave of fake news expected, said Luca Belli, coordinator of the Center for Technology and Society at the Getulio Vargas Foundation, a university in Rio de Janeiro.

Takedown orders are common during campaigns, and not having someone receive legal notices would make timely compliance impossible.

Hours after the judge's ruling, Musk said on X that Moraes "has repeatedly broken the laws he has sworn to uphold."

Previously, he had called the judge's decisions regarding X "unconstitutional".

Musk on Wednesday called Moraes "an evil dictator playing judge" after he posted a post from X saying it was expected to close "soon" in Brazil.

The dispute between Musk and the judge began earlier this month when X claimed that one of his legal representatives in Brazil had been threatened with arrest if they did not comply with legal orders to remove some content from the platform.

X, which is accessed by 40 million Brazilians at least once a month, responded by announcing it would close its operations and lay off its staff in Brazil because of what it called a "censorship order" from the judge.

Its service will remain available to users in Brazil, he said.

Earlier this year, Moraes ordered X to block several accounts implicated in investigations into so-called "digital militias" that have been accused of spreading fake news and hate messages during the government of former far-right president Jair Bolsonaro.

After Musk contested that decision and said he would reactivate X accounts that a judge had ordered blocked, Moraes opened an investigation into the billionaire in early April./SkyNews