The United States on Tuesday imposed fresh sanctions on a network of companies and people in Iran, Turkey and the United Arab Emirates it said was transferring billions of dollars and euros to Iran's elite Revolutionary Guards.

The U.S. Treasury said it was blacklisting 25 people and entities, including front companies based in the three countries, associated with Iran's Islamic Revolutionary Guards Corps and the Ministry of Defense and Armed Forces Logistics, or MODAFL.

The targeted institutions include banks and other financial institutions, including Ansar Bank, Atlas Exchange, Iranian Atlas Company.

"We are targeting a vast network of front companies and individuals located in Iran, Turkey, and the UAE to disrupt a scheme the Iranian regime has used to illicitly move more than a billion dollars in funds," Treasury Secretary Steven Mnuchin said in a statement.

Mnuchin said the IRGC and MODAFL continued to try to evade sanctions to help Iran's government fund terrorism and destabilize the Middle East.

Washington reimposed sanctions against Iran after President Donald Trump withdrew from a 2015 nuclear deal between Tehran and six world powers, and moved to isolate Tehran. It has also imposed a string of new sanctions, including against the IRGC and its external arm, Quds Force, to choke off funding for its overseas operations.

The IRGC is by far Iran's most powerful security organization and has control over large stakes in Iran's economy and huge influence in its political system.