Far-right former Brazilian president Jair Bolsonaro was admitted to a hospital in Florida on Monday with stomach pains as 1,500 of his supporters were rounded up in Brasilia after storming key buildings in the capital at the weekend.
President Luiz Inacio Lula da Silva, a leftist who took office on January 1 after defeating Mr Bolsonaro in an October election, vowed to bring those responsible to justice.
He accused rioters of trying to overthrow democracy and questioned why the army had not discouraged calls for a military coup outside their barracks.
On Sunday, angry mobs rampaged through Congress, the Supreme Court and presidential offices, smashing windows, furniture and artwork in the worst attack on state institutions since Brazil's return to democracy in the 1980s.
Mr Bolsonaro, who flew to the US days before his term in office ended, went to a hospital in Orlando on Monday complaining of intestinal pain related to a stabbing he suffered during the 2018 election campaign.
His doctor said he has an intestinal blockage that was not serious and would probably not need surgery.
In an interview with CNN Brasil, Mr Bolsonaro said he had planned to stay in the US until the end of January, but now plans to go back to Brazil sooner to see his doctors.
“I intend to bring forward my return because in Brazil the doctors already know about my problem of intestinal obstruction due to the stab wound,” he said.
Mr Bolsonaro faces several investigations before the Supreme Court in Brazil and his future in the US — where he travelled with a visa issued to heads of state, diplomats and other government officials — is in question.
Representative Joaquin Castro, a Democratic member of the US Congress, said on CNN that the US should not give refuge to an “authoritarian who has inspired domestic terrorism”.
Mr Castro urged the Biden administration to send Mr Bolsonaro back to Brazil.
The US government declined to comment on former Brazilian president's current visa status.
US State Department spokesman Ned Price said a person who entered on a visa for foreign officials must depart the country within 30 days or apply for a change of immigration status if they are no longer engaged in official business.
Restoring order in the Brazilian capital, Brazilian soldiers backed by police on Monday dismantled a two-month-old protest camp opposite the army's headquarters.
The camp had served as the base for Mr Bolsonaro's supporters who have been protesting since his electoral defeat.
About 1,200 people from the camp were detained for questioning on Monday, authorities said, after about 300 arrests on Sunday.
Thousands of Mr Bolsonaro's backers set off from that encampment on Sunday before storming the presidential palace, the Supreme Court and Congress.
Mr da Silva, popularly known as Lula, was back at work at the ransacked Planalto palace, where he met his defence minister and commanders of the armed forces to discuss the violence, reminiscent of the assault on the US Capitol two years ago by backers of former president Donald Trump.
Speaking later to the country's governors, Mr da Silva, 77, stepped up his criticism of the Brazilian military for tolerating demonstrations at their gates calling for a coup since Mr Bolsonaro lost the election.
“People were openly calling for a coup outside the barracks, and nothing was done. No general lifted a finger to tell them they could not do that,” he said.
He accused some security forces of being complicit with rioters.
US President Joe Biden joined other world leaders in condemning Sunday's riots, calling them “outrageous”, while Mr Bolsonaro, who is now in Florida, denied inciting his supporters and said the rioters had “crossed the line”.
In a phone call on Monday, Mr Biden invited Mr da Silva to visit Washington in early February, according to the White House.
Pro-Bolsonaro lorry drivers, who have caused intermittent havoc on Brazil's motorways for months, held more protests through Sunday night.
The lorry drivers are among Mr Bolsonaro's supporters who refuse to accept the result of the October election, seeking to cause economic disruption to provoke a military coup.
Police on Monday removed their blockade of the BR 163 motorway that cuts through Brazil's top grain-producing state Mato Grosso and on another motorway in Parana state.
Supreme Court Justice Alexandre de Moraes on Sunday ordered the suspension of Brasilia's governor for 90 days over alleged security failings and demanded that social media platforms Facebook, Twitter and TikTok block the accounts of users spreading anti-democratic propaganda.
Facebook parent Meta and Google's video platform YouTube said on Monday that they were removing content supporting or praising the weekend actions.
TikTok and Twitter did not respond to requests for comment.
Brazil's financial markets held steady after an early drop, with the Bovespa benchmark stock index edging higher in afternoon trading and the currency closing 0.4 per cent weaker against the US dollar.
Some analysts said Sunday's violence could strengthen Mr da Silva politically.
