Leftist President Luiz Inacio Lula da Silva, who defeated Bolsonaro in the most fraught election in a generation last year, announced a federal security intervention in Brasilia lasting until January 31 after capital security forces initially were overwhelmed by the invaders.

In a press conference, he blamed Bolsonaro and complained about a lack of security in the capital, saying authorities had allowed “fascists” and “fanatics” to wreak havoc.

“These vandals, who we could call fanatical Nazis, fanatical Stalinists … fanatical fascists, did what has never been done in the history of this country,” said Lula, who was on an official trip to Sao Paulo state.

“All these people who did this will be found and they will be punished.”

WATCH: Video of the events in Brazil

The sight of thousands of yellow-and-green clad protesters running riot in the capital capped months of tension following the October 30 vote.

Bolsonaro, an acolyte of Trump’s who has yet to concede defeat, peddled the false claim that Brazil’s electronic voting system was prone to fraud, spawning a violent movement of election deniers.

There was no immediate word from Bolsonaro, who has barely spoken in public since losing the election. He flew to Florida 48 hours before the end of his mandate and was absent from Lula’s inauguration.

“This genocidist … is encouraging this via social media from Miami,” Lula said, referring to Bolsonaro.

“Everybody knows there are various speeches of the ex-president encouraging this.”

The violence in Brasilia could amplify the legal risks Bolsonaro faces. It also presents a headache for US authorities as they debate how to handle his stay in Florida.

About 6.30pm local time, some three hours after the initial reports of the invasion, security forces managed to retake the three buildings, GloboNews reported. TV images showed dozens of rioters being led away in handcuffs.

The invasions were condemned by leaders around the world.

US President Joe Biden, whose own presidency was marked by a similar event, said the situation was “outrageous”. His Secretary of State Antony Blinken offered Washington’s full support to Lula and Brazil’s institutions.

“Using violence to attack democratic institutions is always unacceptable,” Blinken wrote on Twitter. “We join Lula in urging an immediate end to these actions.”

The invasion poses an immediate problem for Lula, who was only inaugurated on January 1 and has pledged to unite a nation torn apart by Bolsonaro’s nationalist populism.

Television images showed protesters breaking into the Supreme Court and Congress, chanting slogans and smashing furniture. Local media estimated about 3000 people were involved.

The Supreme Court, whose crusading Justice Alexandre de Moraes has been a thorn in the side of Bolsonaro and his supporters, was ransacked by the occupiers, according to social media images that showed protesters clubbing security cameras and shattering the windows of the modernist building.

On Saturday, with rumours of a confrontation brewing in Brasilia, Justice Minister Flávio Dino authorised the deployment of the National Public Security Force. On Sunday, he wrote on Twitter, “this absurd attempt to impose the will by force will not prevail.”

In Washington in 2021, Trump supporters attacked police, broke through barricades and stormed the Capitol in a failed effort to prevent congressional certification of Joe Biden’s 2020 election victory.

Trump, who has announced a third bid for the presidency, in 2024, had pressured his vice president, Mike Pence, not to certify the vote, and he continues to claim falsely that the 2020 election was stolen from him through widespread fraud.

-AAP