A local official from Brazil's leftist opposition Workers' Party (PT) was shot dead on Saturday by a federal prison guard shouting support for rightwing President Jair Bolsonaro, according to a state civil police report and a witness.

Marcelo Arruda, a municipal guard and PT official, was celebrating his birthday party in the southern Brazilian city of Foz de Iguacu, in the state of Parana, when Jorge Jose da Rocha Guaranho entered the event and shot him dead.

Arruda, who was also armed, shot back, killing Guaranho, according to a PT statement.