Former Brazilian president Jair Bolsonaro was admitted to hospital in the US state of Florida a day after his supporters stormed government buildings in protest against his electoral defeat last year.
He "is under observation in the hospital due to abdominal discomfort stemming from the stabbing attack he suffered in 2018", his wife Michelle Bolsonaro wrote on Instagram.
Mr Bolsonaro earlier on Monday denied accusations by President Luiz Inacio Lula da Silva that he had incited Sunday's assault on Brazil's seat of power in Brasilia.
Supporters of Mr Bolsonaro, who has yet to concede the election held in October, invaded the Congress, Supreme Court and presidential palace buildings in Brasilia on Sunday. At least one police vehicle was burnt.
The rioters, some carrying the national flag, smashed windows and threw furniture in scenes reminiscent of the January 6, 2021, insurrection at the US Capitol after former president Donald Trump's election loss.
“Throughout my mandate, I have always been within the four lines of the constitution, respecting and defending the laws, democracy, transparency and our sacred freedom,” Mr Bolsonaro wrote on Twitter.
He said that while peaceful demonstrations are “part of democracy”, the invasion of public buildings was not.
At least 1,200 people have been detained, the Ministry of Justice said on Monday. Mr da Silva said that those connected to the attack “will be found and punished”.
The riots in Brasilia, the administrative capital, come after weeks of protests by Bolsonaro supporters who refuse to recognise the election victory by Mr da Silva, who was inaugurated last week.
The crowds were eventually dispersed by police, but they left behind messages scrawled on the walls, including a call for “military intervention” and one lamenting the “destitution” of the three branches of government.
In a joint statement with both houses of Congress and the Supreme Court's chief justice, Mr da Silva on Monday condemned Mr Bolsonaro's supporters.
The three branches of government condemned the riots as “terrorist acts and criminal, coup-mongering vandalism”.
“We are united so that institutional measures are taken under the terms of Brazilian laws,” the statement said.
Mr da Silva also shared a picture of him with Lower House Speaker Arthur Lira, acting Senate President Veneziano Vital do Rego and Chief Justice Rosa Weber at Planalto Palace.
Images showed members of the Brazilian military dismantling the tents of protesters who had been camping near army headquarters in Brasilia.
The government had given protesters until noon local time to leave the site, Reuters reported.
Mr da Silva accused Mr Bolsonaro of inciting the attack through his speeches.
“There are several speeches by the former president encouraging this. And this is also his responsibility and the parties that supported him,” he wrote on Twitter.
“They took advantage of the silence on Sunday, while we are still setting up the government, to do what they did.”
The President, who was visiting the flood-hit city of Araraquara in the south-eastern state of Sao Paulo, flew back to Brasilia to oversee the response to what he called a “fascist” attack.
Mr da Silva said the local militarised police force that reports to Brasilia governor Ibaneis Rocha, a former Bolsonaro ally, did nothing to stop the advance of the protesters.
The Supreme Court, which described the rioters as “terrorists”, removed the governor from office for 90 days over the failure to protect the state buildings.
Justice Minister Flavio Dino said a number of people were being investigated for allegedly paying for buses to take the demonstrators to the capital.
US President Joe Biden released a joint statement with Mexican President Andres Manuel Lopez Obrador and Canadian Prime Minister Justin Trudeau condemning the efforts of Mr Bolsonaro's supporters to halt the peaceful transition of power in Brazil.
“We stand with Brazil as it safeguards its democratic institutions. Our governments support the free will of the people of Brazil,” the leaders said.
“We look forward to working with President Lula on delivering for our countries, the Western Hemisphere and beyond.”
On Monday, Mr Biden issued a joint statement with Mr da Silva after a call, conveying "the unwavering support of the United States for Brazil’s democracy and for the free will of the Brazilian people as expressed in Brazil’s recent presidential election, which President Lula won".
"President Biden condemned the violence and the attack on democratic institutions and on the peaceful transfer of power."
The statement said Mr da Silva accepted an invitation to meet Mr Biden in a visit to the White House in February.
Bob Menendez, chairman of the Senate Foreign Relations Committee, said the attack on Brazil's government demonstrate how Mr Trump's legacy “continues to poison our hemisphere”.
Mr Bolsonaro had left Brazil for the US two days before his term ended. He travelled to Florida under a visa that is only given to former presidents, Reuters reported.
Speaking to CNN, US Democratic Congressman Joaquin Castro denounced Mr Bolsonaro's stay in Florida.
“The United States should not be a refuge for this authoritarian who has inspired domestic terrorism in Brazil. He should be sent back to Brazil.”
National Security Adviser Jake Sullivan told reporters that the US has not received an official extradition request from the Brazilian government.
Mr Sullivan did not speak on Mr Bolsonaro's visa status.
"On this particular case, this particular individual, again, I have to proceed with extreme caution in terms of how I talk about it because of the legal issues and the precedent issues involved," Mr Sullivan said.
Mr Bolsonaro went 44 hours without making public remarks after his October defeat. During that window, his supporters blocked motorways and called for a military coup to prevent Mr da Silva's return to power.
Agencies contributed to this report