Brazilian prosecutors have made a formal allegation of tax evasion and money laundering against former tourism minister Henrique Alves.
Mr Alves resigned on Thursday after being linked to a corruption scheme.
Brazil's Prosecutor General Rodrigo Janot presented evidence to the Supreme Court saying that Mr Alves had a secret bank account in Switzerland.
He became the third cabinet minister to stand down since interim President Michel Temer came to power last month.
All are implicated in a major corruption scandal at the state oil company, Petrobras.
Mr Alves denied the allegations.
On Wednesday, the Supreme Court released testimony by an ex-executive implicating 20 politicians including Mr Temer.
In a television broadcast, Mr Temer dismissed the testimony as frivolous lies.
'To avoid embarrassing'
The allegations come from Sergio Machado, the former chief executive of Petrobras subsidiary Transpetro.
Mr Machado is himself under investigation and has made a plea bargain with prosecutors.
He said that both Mr Temer and Mr Alves asked him for money for electoral campaigning and knew it would come from an illegal kickbacks scheme that diverted billions of dollars from the national oil company.
Mr Alves also denied the accusations against him and said on social media that contributions to his campaigns had been made through official channels and declared to election authorities.
He said on Thursday that he was resigning in order "to avoid embarrassing" the government.
Henrique Alves, a member of Mr Temer's PMDB party, is the third minister to step down after former Transparency Minister Fabiano Silveira and former Planning Minister Romero Juca both resigned over leaked phone recordings linked to the Petrobras scandal.
Mr Temer took office on 12 May after the Senate voted to begin an impeachment trial against President Dilma Rousseff for breaking the law in the management of last year's budget.
She said the accusations were politically-motivated and described the impeachment proceedings against her as a coup.