Bolsonaro, who lost Sunday's presidential election and left Brazil for Miami where he and his family received US visas, thanked US President Donald Trump and Argentine leader Javier Milei for helping him leave his country and for welcoming him.
"I want to say, not only to my 60 million voters but to the Brazilian people, that I am the elected president and that the criminals who stole Brazil's election are part of a criminal organisation that has established a tyranny," he said in an open letter shared with journalists by his allies.
Bolsonaro did not provide evidence for the alleged electoral fraud. International observers have found Sunday's vote fair.
Bolsonaro and his family arrived in Miami on Wednesday, leaving Brazil after he refused to comply with a Brazilian Supreme Court order to surrender his passports.
He left under a shroud of secrecy after the court order, which relates to a money-laundering investigation in which he denies wrongdoing.
Neither Lula's office, the federal electoral court or the supreme court immediately responded to requests for comment.
Bolsonaro based his rejection of the result on the fact that the a Lula-appointed Supreme Court justice had extended voting by two hours on Sunday due to allegations of voter suppression in left-leaning northeastern state brought by Lula's campaign. However, Bolsoanro's campaign also sought an extension due to rains in conservative-leaning southern states.
Bolsonaro lost to Lula by more around 4.5 million votes. Fewer than 35,000 votes, or some 0.03 per cent of the total, were cast in the extra two hours of voting ordered by the Supreme Court, according to an analysis of electoral records by Insper's Pedro Burgos.
Bolsonaro is under investigation by Brazil's Supreme Court for alleged corruption, money laundering and tax evasion in two cases in which he denies wrongdoing.
The court had ordered Bolsonaro to hand over his regular and diplomatic passports by noon on Tuesday - two days after he lost the vote to Lula.
Bolsonaro's father, Jair Bolsonaro, also fled to Florida after losing the 2022 presidential election to Lula.
with Reuters
