President Dilma Rousseff says the investigation into kickbacks at Brazil's state oil company could forever change the relationship among society and the country's state and private companies.

Rousseff spoke to mostly Brazilian reporters at a Sunday news conference in Brisbane, Australia, where a two-day summit with world leaders was ending. Her office posted a video of her comments online.

The president says the probe of the oil firm Petrobras signals "an end to impunity" in corruption cases.

Authorities allege top Petrobras officials operated a kickback scheme on contracts involving several billion dollars, with the money later going back to the governing Workers Party and other top parties for political campaigns.

Police on Friday arrested Renato Duque, the former director of services of Petrobras, for his alleged role in the scheme.