By Gary Duffy
BBC News, Sao Paulo
Police are investigating Brazil's energy minister over a corruption scheme involving public works at the centre of a major investigation.
Silas Rondeau has denied any wrongdoing
More than 50 people have been arrested in the inquiry, the latest in a series of scandals involving politicians.
Silas Rondeau, who has denied any wrongdoing, is the most prominent figure yet to be involved.
During a visit to Paraguay with the Brazilian president, Mr Rondeau told reporters: "You cannot prove a lie."
In a report widely carried in the Brazilian media, police said they suspected the minister may have received a payment of over $50,000 (£25,000) from a company that won a contract to provide electricity to rural areas across the country.
The justice minister later said the report was authentic, but there was no proof to directly implicate his ministerial colleague.
The police investigation, called "Operation Navalha" - or Straight Razor - has focused on claims of fraud involving public works, including the building of bridges in isolated areas that were never completed.
An ex-governor, several mayors and ex-mayors, as well as several high-level state and federal employees, are among those who have been arrested as part of the investigation.
The incident is just the latest scandal to blight Brazilian political life and the fact that the arrests were spread across several parties seems likely to further undermine public trust.