Tens of thousands of Brazilians are marching in cities demanding President Dilma Rousseff's impeachment and blasting what they say is deep government corruption.

In many instances, demonstrators openly called for a military coup to dissolve the government.

The Sunday marches were peaceful, with families wearing shirts with colors of the Brazilian flag and holding placards demanding Rousseff's ouster.

The demonstrations come amid an inquiry into a kickback scheme at state-run oil company Petrobras, which prosecutors call the biggest corruption case yet uncovered in Brazil.

Prosecutors are investigating dozens of top congressman and current and former executive branch members for alleged involvement. Rousseff herself hasn't been implicated.

But those marching Sunday say corruption is endemic in Brazilian politics and demand that virtually the entire political class be forced out.