Police made several new arrests Friday during fresh raids in a probe into money laundering accusations against crisis-hit President Dilma Rousseff's party.

The federal police said in a statement it launched "a new front in investigations" into a "money laundering scheme" involving the ruling Workers' Party (PT).

The sprawling scandal threatens to bring down the government of Latin America's biggest economy, which hosts the Olympic Games in August.

Police said they had warrants to detain two people and question two more, including former PT treasurer Delubio Soares, who was jailed over a previous bribery scandal involving the party.

Friday's raids in Sao Paulo were part of Operation Car Wash, a wide-ranging investigation into corruption at state oil firm Petrobras.

Rousseff faces impeachment proceedings alongside a separate set of allegations of financial wrongdoing.

Her fight against impeachment gathered speed Thursday when tens of thousands of people marched nationwide to oppose what they branded a "coup" against her.

Rousseff's chief ally in the crisis -- ex-president Luiz Inacio Lula da Silva -- meanwhile won a court battle that removes him from the jurisdiction of a crusading anti-corruption judge.

Friday's raids aim "to deepen the investigation into the money laundering scheme" involving a bank linked to Petrobras and cash that was allegedly used to pay off PT debts, the police statement said.