A top Brazilian newspaper is reporting that popular former President Luiz Inacio Lula da Silva will be investigated for allegations that he knew about a massive cash-for-votes scheme, the nation's biggest corruption scandal.

The Estado de S. Paulo newspaper reports Wednesday that the attorney general has ordered the formal investigation. It cited no sources.

Before hours call to the attorney general's office weren't answered.

The same newspaper first reported last month that businessman Marcos Valerio told prosecutors that Silva knew of the scheme and financially benefited from it.

Silva denies any connection to the scheme, which became public in 2005.

Valerio came forward with his accusations in September after he was convicted but before his sentencing — he received 40 years in prison for his leading role in the scheme.