A man who stabbed Brazilian president Jair Bolsonaro at a campaign rally last year has been acquitted on the grounds that he was mentally ill.

Adelio Bispo de Oliveira stabbed his country’s leader with a knife in the streets of Juiz de Fora, north of Rio de Janeiro, piercing the his intestine and putting his life in danger.

Mr Bispo was then badly beaten by Mr Bolsonaro’s supporters.

Judge Bruno Savino ruled that Mr Bispo should be treated in a mental facility within the federal prison system to minimise the risk of escape or another attack.

“The hospitalisation will last for an indefinite period until medical experts have proven that he is no longer dangerous,” Mr Savino said in a statement.

Jair Bolsonaro: Brazil's far-right leader inauguration Show all 20 1 /20 Jair Bolsonaro: Brazil's far-right leader inauguration Jair Bolsonaro: Brazil's far-right leader inauguration Brazil's new President Jair Bolsonaro waves as he drives past before his swear-in ceremony Reuters Jair Bolsonaro: Brazil's far-right leader inauguration Supporters wait in front of the Planalto Palace, where he will take office EPA Jair Bolsonaro: Brazil's far-right leader inauguration Jair Bolsonaro gestures at the Congress before he is sworn AFP/Getty Jair Bolsonaro: Brazil's far-right leader inauguration Supporters take pictures as Brazil's new President Jair Bolsonaro drives past Reuters Jair Bolsonaro: Brazil's far-right leader inauguration Flanked by first lady Michelle Bolsonaro, Brazil's President Jair Bolsonaro waves to the crowd, as he rides in an open car after his swearing-in ceremony AP Jair Bolsonaro: Brazil's far-right leader inauguration Jair Bolsonaro reacts as he drives past Reuters Jair Bolsonaro: Brazil's far-right leader inauguration Brazil's new President Jair Bolsonaro reacts as he drives past before his swear-in ceremony, in Brasilia, Brazil January 1, 2019. REUTERS/Ricardo Moraes RICARDO MORAES Reuters Jair Bolsonaro: Brazil's far-right leader inauguration The National Congress before Brazil's President-elect Jair Bolsonaro is sworn in AFP/Getty Jair Bolsonaro: Brazil's far-right leader inauguration Jair Bolsonaro gestures at the Congress AFP/Getty Jair Bolsonaro: Brazil's far-right leader inauguration Brazil's new President Jair Bolsonaro waves as he drives past before his swear-in ceremony, in Brasilia, Brazil January 1, 2019. REUTERS/Ricardo Moraes RICARDO MORAES Reuters Jair Bolsonaro: Brazil's far-right leader inauguration Supporters of Brazil's President Elect Jair Bolsonaro are cooled down with a water hose by firefighters, prior Bolsonaro's inauguration, in Brasilia, Brazil, Tuesday Jan. 1, 2019. (AP Photo/Silvia Izquierdo) Silvia Izquierdo AP Jair Bolsonaro: Brazil's far-right leader inauguration The presidential convoy, led by Brazil's President-elect Jair Bolsonaro (L) and his wife Michelle Bolsonaro in a Rolls Royce, heads to the National Congress for his swearing-in ceremony, in Brasilia on January 1, 2019. - Bolsonaro takes office with promises to radically change the path taken by Latin America's biggest country by trashing decades of centre-left policies. (Photo by Carl DE SOUZA / AFP)CARL DE SOUZA/AFP/Getty Images CARL DE SOUZA AFP/Getty Jair Bolsonaro: Brazil's far-right leader inauguration epa07257163 Sympathizers of Brazilian President-elect, Jair Bolsonaro, walk past a giant figure of the future president before the beginning of the inauguration ceremony, in Brasilia, Brazil, 01 January 2019. A far-right president leads the biggest Latin America democracy for first time since the end of military rule (1964-1985). Bolsonaro defeated candidate Fernando Haddad in the runoff, held in October 2018, receiving 55 percent of the vote. EPA/Fernando Bizerra Jr Fernando Bizerra Jr EPA Jair Bolsonaro: Brazil's far-right leader inauguration Brazil's President-elect Jair Bolsonaro (L) gestures next to his wife Michelle Bolsonaro as the presidential convoy heads to the National Congress for his swearing-in ceremony, in Brasilia on January 1, 2019. - Bolsonaro takes office with promises to radically change the path taken by Latin America's biggest country by trashing decades of centre-left policies. (Photo by Carl DE SOUZA / AFP)CARL DE SOUZA/AFP/Getty Images CARL DE SOUZA AFP/Getty Jair Bolsonaro: Brazil's far-right leader inauguration Firefighters spray water at supporters of Brazilian President-elect Jair Bolsonaro to cool them down, while they gather to wait for his inauguration ceremony at "Tres Poderes" square in front of the Planalto Palace in Brasilia, on January 01, 2019. - Brazil entered a new chapter in its history on Tuesday, embracing a far-right president, Jair Bolsonaro, whose determination to break with decades of centrist rule has raised both hopes and fears. (Photo by EVARISTO SA / AFP)EVARISTO SA/AFP/Getty Images EVARISTO SA AFP/Getty Jair Bolsonaro: Brazil's far-right leader inauguration Supporters take pictures as Brazil's new President Jair Bolsonaro drives past before his swear-in ceremony, in Brasilia, Brazil January 1, 2019. REUTERS/Ricardo Moraes RICARDO MORAES Reuters Jair Bolsonaro: Brazil's far-right leader inauguration Brazil's new President Jair Bolsonaro and his wife, Michelle Bolsonaro, arrive at Brazil's National Congress, in Brasilia, Brazil January 1, 2019. REUTERS/Pilar Olivares PILAR OLIVARES Reuters Jair Bolsonaro: Brazil's far-right leader inauguration Supporters of Brazilian President-elect Jair Bolsonaro, gather at the "Tres Poderes" square in front of the Planalto Palace in Brasilia, before his inauguration ceremony on January 01, 2019. - Brazil entered a new chapter in its history on Tuesday, embracing a far-right president, Jair Bolsonaro, whose determination to break with decades of centrist rule has raised both hopes and fears. (Photo by EVARISTO SA / AFP)EVARISTO SA/AFP/Getty Images EVARISTO SA AFP/Getty Jair Bolsonaro: Brazil's far-right leader inauguration Supporters of Brazilian President-elect Jair Bolsonaro, gather to wait for his inauguration ceremony at "Tres Poderes" square in front of the Planalto Palace in Brasilia, on January 01, 2019. - Brazil entered a new chapter in its history on Tuesday, embracing a far-right president, Jair Bolsonaro, whose determination to break with decades of centrist rule has raised both hopes and fears. (Photo by EVARISTO SA / AFP)EVARISTO SA/AFP/Getty Images EVARISTO SA AFP/Getty Jair Bolsonaro: Brazil's far-right leader inauguration Jair Bolsonaro addresses Congress, during his swearing-in ceremony as Brazil's new president, in Brasilia on January 1, 2019. - Bolsonaro takes office with promises to radically change the path taken by Latin America's biggest country by trashing decades of centre-left policies. (Photo by NELSON ALMEIDA / AFP)NELSON ALMEIDA/AFP/Getty Images NELSON ALMEIDA AFP/Getty

Mr Bolsonaro said he will appeal the decision. “I will contact my lawyer. I will try to do whatever is possible. They tried to kill me. I am certain who they were,” he said.

He added: “This is a crime against a presidential candidate who now has the mandate and we must go to the final consequences of that situation.”

At the moment of the attack, Mr Bolsonaro was on the shoulders of a supporter, looking out at the crowd and giving a thumbs up with one hand.

The far-right politician suffered a deep and life-threatening wound to his intestines, was placed in intensive care and lost 40 per cent of his blood.

But Mr Bolsonaro went on to win the presidential election.

Since he has been in office, Brazil has turned sharply against LGBT+ rights and feminism, officially criminalising homophobia and transphobia last week.