Prosecutors charged the former treasurer of Brazilian President Dilma Rousseff's party Monday with 24 new counts of money laundering in a corruption scandal involving state oil giant Petrobras and high-ranking politicians.

Joao Vaccari, who resigned as Workers' Party (PT) treasurer after being arrested on April 15, is accused of funneling bribes skimmed off the top of inflated Petrobras contracts to the PT's coffers.

Prosecutors say Petrobras executives colluded with construction companies over the course of a decade to massively overbill the oil giant and use part of the money to bribe politicians, including members of the PT and its allies.

Vaccari has been caught up in several strands of the investigation into the graft at Petrobras, which the company, the largest in Brazil, said last week had cost it $2.1 billion.

In their latest addition to his growing charge sheet, prosecutors accused him of colluding with former Petrobras services director Renato Duque and businessman Augusto Mendonca to launder 2.4 million reals ($830,000) in dirty money through phony contracts with a printing company.

The scheme ran from April 2010 to December 2013, but the trio continued their criminal activity into 2014, failing to realize an investigation was under way, prosecutors said.

They said the scheme also involved two parties allied with the PT, the Progressive Party and the PMDB, a large centrist party seen as essential for doing business in Brasilia.

Money laundering carries a sentence of three to 10 years in prison in Brazil, which could be increased in the case of Vaccari and his co-accused if they are convicted of conspiracy and on multiple counts, prosecutors said.

They calculated the three accused owe the state $2.5 million in stolen Petrobras funds plus damages for the 24 new counts of money laundering.

Vaccari was first charged with corruption and money laundering in the Petrobras case on March 16.