Embattled Brazilian President Dilma Rousseff on Tuesday called her Vice President Michel Temer the "head of the conspiracy" that seeks to remove her from office in her most direct attack on him so far.

Speaking to teachers and students at the Presidential Palace in Brasilia, Rousseff said Temer and Lower House Speaker Eduardo Cunha are working together to gather votes for her impeachment.

A lower house commission on Monday put Rousseff one step closer to impeachment after approving a report in favor of her removal. Hours earlier, a 13-minute-long audio of Temer rehearsing a post-impeachment speech was leaked.

Rousseff said the recording shows Temer has "arrogance and contempt for the people."

"The mask of the conspirators has fallen," she said.

Rousseff is facing impeachment proceedings over allegations her administration violated fiscal rules to mask budget problems by shifting around government accounts ahead of her 2014 re-election.

Opposition parties claim sleight-of-hand accounting moves allowed her to boost public spending to shore up votes. Rousseff has denied any wrongdoing and has not been charged with any crime.

Her opponents say the impeachment process is in line with the wishes of the majority of Brazilians, while Rousseff's supporters call it a blatant power grab by her foes.

In another development, a former senator was detained in the latest sweep in a sprawling corruption investigation here.

Officials said Gim Argello was placed in preventive detention early Tuesday, accused of taking bribes from construction firms involved in the massive bribes scheme at the state-run Petrobras oil company. The bribes were allegedly in exchange for Argello's help in keeping the firms' executives from being called to appear before parliamentary committees investigating the scheme.

Federal prosecutor Carlos Fernando de Lima said the illicit funds were then passed on as legal donations to political parties.

Lima told journalists at a news conference the practice "has existed for a long time."

He said that "corruption in Brazil is not partisan."

Argello's aide and another person were temporarily detained in the sweep.