The United States unveiled sanctions Thursday against two companies in the Central African Republic for supporting the Russian Wagner Group's security operations and illegal mining activities in the country.

The Treasury Department said in a statement that it had designated the CAR-based Mining Industries for leasing aircraft from another sanctioned Emirati firm which Wagner used to transport personnel and equipment across Africa.

It also sanctioned Logistique Economique Etrangere for receiving "hundreds" of shipments of heavy materials from another CAR-based company -- which was sanctioned in March this year -- that were also likely intended for Wagner-linked illicit mining activities.

Mining activities are a key revenue source for the US-sanctioned, Russian government-funded private military company (PMC), which has operated in countries across north, central and west Africa.

Wagner Group also played an important role in the Russian invasion of Ukraine.

"The Russia-backed Wagner Group and its network of businesses have exploited the people and natural resources of the Central African Republic to advance the group’s agenda," Brian Nelson, US Treasury under secretary for terrorism and financial intelligence, said in a statement.

"The United States will continue to use its sanctions authorities to disrupt those supporting Russia's destabilizing activities in Africa," Nelson added.

The Wagner Group was previously controlled by Yevgeny Prigozhin until his death in a plane crash last summer that many military analysts said appeared to be deliberate.

The Kremlin has dismissed suggestions that it orchestrated the crash, which came shortly after Prigozhin launched a failed bid to topple Russia's military leadership.