Riograndense, a refinery partnered with Petrobras, sold over 100 million liters of naphtha to Petrodansk.
Authorities are investigating solvent producer Petrodansk for fuel-smuggling and money-laundering operations linked to the First Capital Command (PCC).
The U.S. recently designated the PCC, Brazil's largest criminal gang, as a terrorist organization.
This designation increases legal risks for energy companies linked to the group, Reuters reports.