Jair Bolsonaro, Luiz Inacio Lula da Silva spar in Brazil Presidential debate (VIDEO)

Brazil's main presidential candidates on Sunday locked horns with accusations of corruption and threats to democracy during their first election debate for the presidential polls slated to be held in October.

Far-right President Jair Bolsonaro accused leftist opponent Luiz Inacio Lula da Silva of massive corruption, who in turn laid the blame of "destroying Brazil" on the incumbent.

"Your government was the most corrupt in Brazilian history," said Bolsonaro, taking a jab at Lula over a massive scandal centered on state-run oil giant Petrobras.

The probe had landed the 76-year-old ex-president in prison from 2018 to 2019 on controversial corruption charges, annulled by the country's Supreme Court in 2021.

"It was a kleptocracy, a government based on robbery... What do you want to come back to power for? To do the same thing to Petrobras again?" Bolsonaro said in his fiery attack.

How did Lula respond?

Lula, who held the presidential office from 2003 to 2010, responded with a quick-fire attack of his own and accused Bolsonaro of spreading "untruths."

He said that his government should be remembered for its legacy of economic growth and the measures it took to reduce poverty.

"The country I left is a country that people miss, it's the country of employment, where people had the right to live with dignity, with their heads held high," Lula said. "This is the country that the current president is destroying."

Sunday's debate in Sao Paulo featured six of the Latin American nation's 12 presidential candidates.

However, the spotlight is on the popular but tarnished Lula and Bolsnaro, who has been dubbed the "Tropical Trump."

Who is leading in the opinion polls?

Projections show a double-digit advantage for Lula over Bolsonaro, who is eying a come-from-behind win.

Latest opinion polls from the Datafolha institute show 47% votes for Lula and 32% for Bolsanaro.

If no contender manages to win over 50% of valid votes in the first round on October 2, the election will go to a run-off on October 30.

Bolsonaro has also repeatedly attacked Brazil's electronic voting system, leading to concerns that he could contest the result if he suffers a loss.