SAO PAULO, March 17 (Reuters) - Brazil's main opposition party said on Tuesday it would call on the Supreme Court to investigate President Dilma Rousseff's involvement in a corruption scheme at state-run oil firm Petroleo Brasileiro SA .
The motion comes a day after prosecutors charged the treasurer of Rousseff's Workers' Party, Joao Vaccari, with corruption and money laundering, saying that Vaccari was aware that donations he sought for the party were bribe money stolen from Petrobras.
Rousseff has denied knowing about corruption at Petrobras as chairwoman of its board from 2003 to 2010 when much of the alleged graft occurred and has urged a thorough investigation.
She is facing a growing wave of anger over the scandal, however. Some 1 million people protested in two dozen cities on Sunday, many calling for her impeachment.
The president of the opposition PSDB party, Aecio Neves, who narrowly lost last year's presidential election to Rousseff, said in a statement his party would join smaller parties in a Wednesday meeting with Supreme Court Justice Teori Zavascki to ask for the investigation.
The Supreme Court is investigating 34 sitting politicians, including the speakers of both houses of Congress, for allegedly receiving bribe money stolen from Petrobras, but Rousseff is not among them.
Zavascki has previously said there was no evidence to justify an investigation of the president. The Workers' Party says all its campaign donations are legal.
Prosecutors have secured commitments to return 500 million reais ($154 million) of money funneled off of Petrobras contracts to public coffers through plea bargain deals, but suspect much more was stolen.
$1 = 3.24 reais Reporting by Caroline Stauffer; Editing by Leslie Adler