Brazil's Labour Ministry has said it has freed more than 30 people being held in slave-like conditions on the ranch of a senator.
President Lula has announced measures to stop slave labour
Officials said they discovered 32 slave-workers on the ranch of right-wing Senator Joao Ribeiro in the northern state of Para.
They said the captives worked seven days a week without pay and had no running water or toilets.
Senator Ribeiro, of the Liberal Front Party, denies mistreatment.
The Brazilian congress is currently debating a bill to confiscate farms where slavery occurs.
If the bill is passed, the land will be given to some of the 180,000 families waiting in makeshift camps across Brazil for redistributed land.
Labour Ministry inspectors are currently travelling around Brazil making surprise raids, often based on tip-offs, to find out if farmers keep their workers in slavery-like conditions.
Any labourers found are set free.
At the end of January, three officials were shot dead while investigating such allegations.
The killings prompted efforts to speed up passage of the legislation.
Brazil was the last country in the Americas to officially abolish slavery in 1888 and it imported the most slaves from Africa.