The governing party of Brazil has been officially accused of receiving up to $200 million by skimming the funds from the state-owned oil company Petrobras.

Pedro Barusco, the former Petrobras executive, made the accusation against the socialist party at a congressional hearing, alleging that the current treasurer of the Workers' Party had been involved in the scheme.

In response, the Workers' Party has claimed that it received only legal donations.

President Rousseff chaired Petrobras's board for seven years, during the time when much of the corruption is alleged to have taken place.

She has denied knowledge of any corruption.

Barusco, a former executive at Petrobras, is repeating the claims he made in a plea bargain testimony.

He says that he received payments from large engineering and construction companies as long ago as 18 years back. In return for the bribes, the companies received inflated contracts from Petrobras.

Barusco has accused Joao Vaccari, the Worker's Party treasurer, of directly benefiting from the payments.

Last month Vaccari was questioned but was later released. Vaccari’s lawyer as well as the Workers' party assert that the party had accepted only legal donations.

According to a BBC article, Barusco maintains that he did not know who ran the scheme.

And as far as he is aware, Maria das Gracas Silva Foster, the former Petrobras chief officer who along with other senior Petrobras management resigned last month, was in no way involved.

Brazil's Supreme Court, earlier this week, approved the investigation of dozens of politicians for their supposed involvement with the Petrobras-linked kickbacks.

Fifty-four people, mostly politicians who belong to the governing party, are accused of taking bribes. A former president and the speakers of both chambers of Congress are among the accused.

Although many in her party are implicated, President Dilma Rousseff herself has been cleared of any involvement in the scheme.