The Brazilian Bar Association and a Congressman have called for the suspension of Justice Minister Sergio Moro after reports published by an online magazine appear to question Moro's impartiality in a case that saw a former leftist president convicted of corruption.

The Intercept report said that as a crusading anti-corruption judge Moro coordinated with prosecutors in the case that led to the conviction and jailing of former President Luiz Inacio Lula da Silva.

Lula was blocked from running as a presidential candidate because of the conviction in 2018. The leftist leader led opinion polls heading into the October election, which was won by far-right Jair Bolsonaro.

The website said it was only beginning to report on an "enormous trove" of leaked messages between Moro and prosecutors on Telegram, an encrypted messaging platform, that it had received from an anonymous source.

The Bar Association also recommended that all the prosecutors involved in the Car Wash scandal probe be disbanded "so that the investigation can run without any suspicions".

The five-year investigation known as "Car Wash" uncovered billions of dollars of political bribery involving politicians and bureaucrats.

Moro denied any wrongdoing. "There is no orientation in those messages," he told reporters on Monday. He added that he couldn't confirm if the published messages were real because he had not saved them.

In an earlier statement he called the reports "sensationalist". "Regarding the content of the messages citing me, there is no sign of any abnormality or directing of actions as a magistrate, despite them being taken out of context," he said.