Former Brazilian Finance Minister Guido Mantega, who was arrested earlier on Thursday, has been released due to illness in his family.
He had been held as part of investigations into a huge corruption scheme at state oil company Petrobras.
Mr Mantega served as minister from 2006 to 2015 under the governments of former Presidents Luiz Inacio Lula da Silva and Dilma Rousseff.
He was detained at a Sao Paulo hospital where his wife was receiving treatment.
But the judge who ordered the former finance minister's arrest revoked his decision due to illness in his family.
Authorities were not aware of his family's health problems when the temporary arrest was initially issued, said Judge Sergio Moro.
Lawyers for Mr Mantega have not responded to requests for comment.
The arrest comes just days after it was announced that former President Luiz Inacio Lula da Silva would face trial on charges of corruption.
Prosecutors say Lula accepted 3.7m reais ($1.11m; £867,000) in bribes connected to a multi-billion dollar kickback scheme at Petrobras.
The former president has consistently denied the allegations, calling them politically motivated.
Police executed warrants for eight arrests and 32 seizure operations in five states as well as the capital, Brasilia, on Thursday, prosecutors said in a statement.
Apart from Mr Mantega, engineering groups Mendes Junior and OSX Construcao Naval SA, which belong to former commodities tycoon Eike Batista, have also been targeted in the probe known as "Operation X Files".
Federal police said the investigation centred on allegations of corruption over the construction of oil platforms for Petrobras in 2012.
Mendes Junior and OSX Construcao Naval SA could not immediately be reached for comment.