The US Treasury Department lifted sanctions Sunday on Russian aluminum giant Rusal and two related companies after blacklisted billionaire Oleg Deripaska took action to sharply cut his stake in them.

The US has accused Oleg Deripaska of operating for the Russian government. (File Photo)

Rusal, EN+ Group Plc and EuroSibEnergo JSC have "reduced Oleg Deripaska's direct and indirect shareholding stake... and severed his control," the Treasury's Office of Foreign Assets Control (OFAC) said in a statement.

"The companies have also agreed to unprecedented transparency for Treasury into their operations by undertaking extensive, ongoing auditing, certification, and reporting requirements."

The delisting -- first announced in December -- came as the companies sought to avoid being locked out of global markets due to their close association with Deripaska.

The sanctions banned Americans and organizations with US divisions, such as many global banks, from doing business with the companies and froze Deripaska's personal assets in US jurisdictions.

"All sanctions on Deripaska continue in force," the OFAC said.