The United States Tuesday imposed sanctions on nearly 50 entities and people it accused of moving billions of dollars for Iran's military, as Washington seeks to increase pressure on Tehran.

The U.S. Treasury Department in a statement said those targeted Tuesday constitute a "shadow banking network" used by Iran's Ministry of Defense and Armed Forces Logistics (MODAFL) and Islamic Revolutionary Guard Corps (IRGC), both of which are under U.S. sanctions.

The network helped MODAFL and IRGC gain access to the international financial system and process the equivalent of billions of dollars since 2020, the Treasury said.

"The United States is taking action against a vast shadow banking system used by Iran’s military to launder billions of dollars of oil proceeds and other illicit revenue," Deputy Treasury Secretary Wally Adeyemo said in the statement.

Tuesday's action targeted dozens of cover companies in Hong Kong, the United Arab Emirates and Marshall Islands, as well as Iran and Turkey-based firms.

The move freezes any of their U.S. assets and generally bars Americans from dealing with them. Those that engage in certain transactions with them also risk being hit with sanctions.