WASHINGTON — The United States on Thursday imposed sanctions on two Central African Republic companies linked to Russia’s Wagner mercenary group and to illicit mining activities, the Treasury Department said.

Washington, which has previously accused Wagner of advancing what it described as Russia’s “malign activities” in the African country, said the group and related companies had “established a vast security and business network” there.

“This network has advanced Russia’s destabilizing activities at the expense of the Central African Republic’s sovereignty,” the department said in a statement.

One of the companies affected is a mining group which Washington says imported chemicals commonly used in mining, and leased aircraft that Wagner used to move personnel and equipment.

The other is a firm which received shipments of materials from a Russian entity linked to Yevgeny Prigozhin - the group’s founder who was killed in a plane crash last August.

The Treasury said the sanctions meant that all property and interests of the companies that are in the United States, or in the possession or control of U.S. persons, are blocked, adding that financial institutions and other persons that engage in certain transactions or activities with the firms may expose themselves to sanctions.

The United States has sanctioned numerous entities and individuals globally that support the Wagner Group.

Reporting by Katharine Jackson and David Ljunggren; Writing by Paul Grant; Editing by Rami Ayyub and David Holmes