The treasurer of Brazil's ruling Workers' party (PT), Joao Vaccari, was arrested Wednesday in connection with the widening probe into corruption at oil giant Petrobras, federal police said.

Vaccari was arrested in Sao Paulo and will be transferred to Curitiba in southern Parana state, where a judge is leading the probe into the massive corruption scandal, officials told AFP.

Vaccari and some three dozen other politicians have been accused in the scandal that has embroiled the party of President Dilma Rousseff, according to investigators.

The socialist party treasurer is one of the biggest names so far to fall under suspicion in the massive scandal that has gripped Brazil, and quickened calls for the resignation of President Dilma Rousseff, who has not been implicated as yet.

Rousseff was the company's board chair during much of the time when the alleged corruption took place.

The decade-long scheme, which involved inflated contracts and political payoffs, is estimated to have cost Petrobras $3.8 billion.