(Adds details on Justice minister, paragraphs 6-7)
SAO PAULO, Jan 7 (Reuters) - Brazilian prosecutors are investigating text messages from an engineering executive that may show President Dilma Rousseff's chief of staff favored construction firms that donated to his party while he was state governor, the Estado de S. Paulo newspaper reported on Thursday.
A separate set of messages from the same executive may indicate Aldemir Bendine, chief executive of state-run oil company Petrobras, participated in a "supposedly illegal" debenture scheme to raise money for engineering firm OAS when he led the state-run Banco do Brasil, the report said.
Both sets of messages are being analyzed by federal prosecutors, said the paper, which had access to the documents.
Neither Bendine nor Rousseff's chief of staff, Jacques Wagner, have been charged with wrongdoing. Wagner was governor of Bahia state at the time of the messages.
Wagner issued a statement criticizing the leak and said his political activity had always been based exclusively on the interests of Brazil and Bahia.
Justice Minister Jose Eduardo Cardozo ordered a police inquiry into the leaking of the text messages that were protected by legal confidentiality, according to a ministry statement.
Federal police investigators have complained recently about a cut in funding that could hamper ongoing probes. Cardozo has said the government will fully finance police operations.
Investigators are tackling Brazil's largest-ever corruption scandal which has ensnared dozens of politicians, many of whom are aligned with Rousseff's Workers' Party.
Brazil's federal prosecutor's office declined to comment.
Estado said messages from OAS executive Leo Pinheiro appear to show him negotiating donations to the campaign of the Workers' Party candidate for mayor of Salvador in 2012 in exchange for favors from Wagner such as asking the transportation minister to release funds for projects in 2014.
Pinheiro has been sentenced to 16 years in prison for corruption and money laundering.
Television station Globo News reported text messages from Pinheiro also showed him arranging donations for Rousseff's 2014 re-election campaign with Edinho Silva, who was her campaign's treasurer and is now her spokesman.
Bendine is mentioned in text messages from Pinheiro to other executives and House Speaker Eduardo Cunha, who has been formally charged with taking bribes. OAS is suspected of paying bribes to politicians, including Cunha, in exchange for investment from the state-run banks and pension funds.
Estado said Bendine negotiated a 500 million-reais debenture acquisition from OAS in 2014 and Pinheiro had previously asked him about opening financing from pension funds.
Prosecutors are suspicious of a message Pinheiro received from his secretary, in which Bendine insists on speaking with Pinheiro over a fixed phone line, according to Estado.
Petroleo Brasileiro SA, as Petrobras is formally known, did not respond to requests for comment, though Estado published a note from Bendine saying all the projects presented to Banco do Brasil by clients were "completely technical." (Reporting by Caroline Stauffer; Editing by Cynthia Osterman and Matthew Lewis)