Brazilian presidential candidate Flavio Bolsonaro casts his vote in Rio de Janeiro in the country's presidential runoff on Sunday.

The race pits incumbent President Luiz Inacio Lula da Silva of the Workers' Party against Bolsonaro, a senator and eldest son of former President Jair Bolsonaro, campaigning on tougher measures against organised crime, tax and spending cuts and a smaller government.

Backed by his father, Bolsonaro also supports an amnesty that could benefit the former president and others convicted over efforts to overturn the 2022 election result. Jair Bolsonaro is serving a 27-year prison sentence over a failed coup plot and is barred from holding public office.

Senator Flavio Bolsonaro narrowly topped the first round, securing 47.03% of valid votes against 45.16% for Lula.

Recent opinion polls point to a closely contested runoff, with surveys giving Bolsonaro 51% of valid voting intentions and Lula 49%, placing the candidates within the poll's two-percentage-point margin of error.