A Supreme Court judge in Brazil ruled to block popular messaging application Telegram nationwide, barring one of far-right President Jair Bolsonaro's favorite communication channels, in a decision published Friday.

Brazilian President Jair Bolsonaro said that the decision by a Supreme Court judge to block popular messaging app Telegram nationwide is "inadmissible" and puts the "freedom" of Brazilians at risk.

The ruling "is inadmissible. (The judge) failed to act against the two or three people that according to him should be blocked, so he decided to affect 70 million people... What is at stake is our freedom," said the far-right leader, for whom Telegram is a key element of his strategy to win re-election in October.

Citing Telegram's failure to comply with orders from Brazilian authorities and remove messages found to contain disinformation, Judge Alexandre de Moraes ordered the app blocked immediately in Brazil, in a ruling dated Thursday and published Friday on the high court's website.

The decision comes as Bolsonaro gears up to seek reelection in October, facing a popularity slump and counting on Telegram to rally his base.

"Telegram's disrespect for Brazilian law and repeated failure to comply with countless court decisions... is completely incompatible with the rule of law," wrote Moraes.

He said the company had repeatedly refused to comply with rulings and requests from police, the Superior Electoral Tribunal and the Supreme Court itself.

That includes a Supreme Court-ordered investigation into allegations against the Bolsonaro administration of using official communication channels to spread disinformation, he said.

Bolsonaro has openly clashed with Moraes, who ordered him personally investigated in that case.

The president slammed the ruling as "inadmissible" and said it put the "freedom" of Brazilians at risk.

Moraes "failed to act against the two or three people that according to him should be blocked, so he decided to affect 70 million people," Bolsonaro said.

Earlier, Bolsonaro had tweeted a link to subscribe to his channel on Telegram -- which was still operational in Brazil Friday afternoon.

"Our Telegram informs people every day of many important actions of national interest, which many regrettably omit," he said.

"Welcome, and share the truth."

Bolsonaro's minister of justice and security, Anderson Torres, said on Twitter that millions of Brazilians were being "suddenly wronged by an individual decision" and added that his ministry was studying "a solution to give back to the people the right to use the social network," without specifying what measures he intended to adopt.

Moraes's ruling gave Brazil's National Telecommunications Agency (Anatel) 24 hours to suspend Telegram's operations nationwide.

The decision "will have big political and electoral repercussions," tweeted political analyst and digital communications specialist Pablo Ortellado.

"This could move one of the main game pieces of the campaign."

Founded by Russian-born tech entrepreneur Pavel Durov in 2013, Dubai-based Telegram is hugely successful in Brazil, where it has been downloaded on 53 percent of all cell phones.

Durov apologized Friday to the Supreme Court in an Instagram post and blamed a "miscommunication" problem.

"On behalf of our team, I apologize to the Brazilian Supreme Court for our negligence. We definitely could have done a better job," he said.

Bolsonaro, who has had various posts blocked on Facebook, Twitter and YouTube for violating their rules on misinformation, has been eagerly encouraging his base to follow him on Telegram ahead of the October elections.

He trails leftist ex-president Luiz Inacio Lula da Silva, his likely opponent, in the polls.

- Election row -
Moraes also cited Telegram's repeated lack of compliance with efforts by the Superior Electoral Tribunal to get it to cooperate in fighting disinformation in the run-up to the elections.

Telegram was notably absent last month when the tribunal signed an agreement with eight leading social networks to combat disinformation during the elections, including Twitter, TikTok, Facebook, WhatsApp, Instagram and YouTube.

The court's president, Luis Roberto Barroso, wrote to Telegram headquarters in December, asking for a meeting and warning that the app was rife with "conspiracy theories and false information about (Brazil's) electoral system."

Moraes said in his ruling that Telegram "ignored the Brazilian electoral authorities once again, underlining its total contempt for the Brazilian justice system."

The ruling came in a case on a court order that Telegram ignored to block the account of pro-Bolsonaro blogger Allan dos Santos.

Moraes said the company had also refused to comply with a wide range of other orders from Brazilian authorities, including in child pornography cases.

Bolsonaro has more than one million followers on Telegram, not including numerous fan groups with names like "Reelect Bolsonaro 2022."

He faces a series of investigations for spreading false information on social networks, notably over his repeated claims of rampant fraud in Brazil's electronic voting system, for which he has provided no evidence.

Telegram has made its refusal to cooperate with the authorities part of its brand.

It deliberately spreads its encryption keys and chat data on disparate servers around the world so governments cannot "intrude on people's privacy and freedom of expression," it says on its website.