Brazil's public prosecutor on Monday formally accused the ruling Workers' Party (PT) treasurer Joao Vaccari of corruption, including money laundering, relating to the massive kickbacks scandal enveloping state-owned oil firm Petrobras.
Prosecutor Deltan Dallagnol told a news conference in the southern city of Curitiba that Vaccari "urged payment of a portion of bribes in the form of electoral donations" to the party of President Dilma Rousseff, according to testimony collated by investigators.
Vaccari, one of the biggest names yet to fall under suspicion in a snowballing scandal that has gripped Brazil, allegedly received donations worth four million reais, or $1.2 million at current rates.
It comes a day after mass anti-government protests drew more than a million people into the streets.
The graft scheme comprised a 10-year program of kickbacks and political payoffs that allegedly siphoned off $3.8 billion from Petrobras via inflated contracts.
She is not being investigated, but leaders of her ruling coalition in Congress have been named in an ever-widening probe, along with a who's who of Brazilian politicians.
So far, 13 senators, 22 deputies and two governors have been placed under investigation.