Luiz Inacio Lula da Silva and Flavio Bolsonaro take part in the first debate ahead of the presidential election runoff in Sao Paulo. (EPA Images pic)SAO PAULO: Firing off personal attacks, Brazil's President Luiz Inacio Lula da Silva and right-wing senator Flavio Bolsonaro held an acrimonious first debate Sunday, a week before a tight presidential election runoff.

A chaotic exchange between the two men, who called each other liars on multiple occasions, accusing each other of corruption and dragging up various scandals, encapsulated the tone of a bitter election campaign in the deeply polarised nation.

Bolsonaro, 45, son of the far-right former president Jair Bolsonaro, secured a shock first-round lead over Lula earlier this month, and polls predict a close battle for the runoff on Oct 25.