Brazil's President Dilma Rousseff speaks during inauguration ceremony for new Finance Minister Nelson Barbosa at Planalto Palace in Brasilia, Brazil, December 21, 2015. REUTERS/Ueslei Marcelino

SAO PAULO (Reuters) - A federal judge in Brazil authorized President Dilma Rousseff to appear as a witness in an investigation into the use of bribes to influence the passage of legislation, a court spokesman said on Wednesday.

Rousseff, who is not under investigation herself, was called by the defense of businessman Eduardo Valadão, along with other politicians, for the bribery probe known as “Operation Zealots.”

Valadão was charged in November with paying bribes to influence passage of legislation to help the auto industry.

Rousseff could provide written testimony or appear in court, the spokesman said, declining to give more details.

The investigation is separate from a better-known probe into corruption at state-run oil firm Petroleo Brasileiro SA that has ensnared dozens of politicians aligned with Rousseff and weakened her government.

Former President Luiz Inacio Lula da Silva, Rousseff’s predecessor and political mentor, was also called for questioning in “Operation Zealots” as police are investigating whether a payment to one of his son’s companies was a bribe to influence the legislation.